Background: Laparoscopic surgery has led to great clinical improvements in many fields of surgery; however, it requires the use of trocars, which may lead to complications as well as postoperative pain. The complications include intra-abdominal vascular and visceral injury, trocar site bleeding, herniation and infection. Many of these are extremely rare, such as vascular and visceral injury, but may be life-threatening; therefore, it is important to determine how these types of complications may be prevented. It is hypothesised that trocar-related complications and pain may be attributable to certain types of trocars. This systematic review was designed to improve patient safety by determining which, if any, specific trocar types are less likely to result in complications and postoperative pain. Objectives: To analyse the rates of trocar-related complications and postoperative pain for different trocar types used in people undergoing laparoscopy, regardless of the condition. Search methods: Two experienced librarians conducted a comprehensive search for randomised controlled trials (RCTs) in the Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, CINAHL, CDSR and DARE (up to 26 May 2015). We checked trial registers and reference lists from trial and review articles, and approached content experts. Selection criteria: RCTs that compared rates of trocar-related complications and postoperative pain for different trocar types used in people undergoing laparoscopy. The primary outcomes were major trocar-related complications, such as mortality, conversion due to any trocar-related adverse event, visceral injury, vascular injury and other injuries that required intensive care unit (ICU) management or a subsequent surgical, endoscopic or radiological intervention. Secondary outcomes were minor trocar-related complications and postoperative pain. We excluded trials that studied non-conventional laparoscopic incisions. Data collection and analysis: Two review authors independently conducted the study selection, risk of bias assessment and data extraction. We used GRADE to assess the overall quality of the evidence. We performed sensitivity analyses and investigation of heterogeneity, where possible. Main results: We included seven RCTs (654 participants). One RCT studied four different trocar types, while the remaining six RCTs studied two different types. The following trocar types were examined: radially expanding versus cutting (six studies; 604 participants), conical blunt-tipped versus cutting (two studies; 72 participants), radially expanding versus conical blunt-tipped (one study; 28 participants) and single-bladed versus pyramidal-bladed (one study; 28 participants). The evidence was very low quality: limitations were insufficient power, very serious imprecision and incomplete outcome data. Primary outcomes Four of the included studies reported on visceral and vascular injury (571 participants), which are two of our primary outcomes. These RCTs examined 473 participants where radially expanding versus cutting trocars were used. We found no evidence of a difference in the incidence of visceral (Peto odds ratio (OR) 0.95, 95% confidence interval (CI) 0.06 to 15.32) and vascular injury (Peto OR 0.14, 95% CI 0.0 to 7.16), both very low quality evidence. However, the incidence of these types of injuries were extremely low (i.e. two cases of visceral and one case of vascular injury for all of the included studies). There were no cases of either visceral or vascular injury for any of the other trocar type comparisons. No studies reported on any other primary outcomes, such as mortality, conversion to laparotomy, intensive care admission or any re-intervention. Secondary outcomes For trocar site bleeding, the use of radially expanding trocars was associated with a lower risk of trocar site bleeding compared to cutting trocars (Peto OR 0.28, 95% CI 0.14 to 0.54, five studies, 553 participants, very low quality evidence). This suggests that if the risk of trocar site bleeding with the use of cutting trocars is assumed to be 11.5%, the risk with the use of radially expanding trocars would be 3.5%. There was insufficient evidence to reach a conclusion regarding other trocar types, their related complications and postoperative pain, as no studies reported data suitable for analysis. Authors' conclusions: Data were lacking on the incidence of major trocar-related complications, such as visceral or vascular injury, when comparing different trocar types with one another. However, caution is urged when interpreting these results because the incidence of serious complications following the use of a trocar was extremely low. There was very low quality evidence for minor trocar-related complications suggesting that the use of radially expanding trocars compared to cutting trocars leads to reduced incidence of trocar site bleeding. These secondary outcomes are viewed to be of less clinical importance. Large, well-conducted observational studies are necessary to answer the questions addressed in this review because serious complications, such as visceral or vascular injury, are extremely rare. However, for other outcomes, such as trocar site herniation, bleeding or infection, large observational studies may be needed as well. In order to answer these questions, it is advisable to establish an international network for recording these types of complications following laparoscopic surgery.