OBJECTIVE: to understand women's expectations and experience of discomfort during chorionic villus sampling (CVS) and amniocentesis, and relate them to aspects of clinical practice. DESIGN: thematic analysis of narrative interviews. Interviews were recorded and transcribed verbatim, coded and analysed using computer-assisted qualitative data analysis software. PARTICIPANTS AND SETTING: sample recruited nationally for two wider studies of experiences of antenatal screening (n=47) and experiences of ending a pregnancy for fetal abnormality (n=40). Of these, 31 women had experienced amniocentesis and/or CVS at least once. FINDINGS: most women found the procedures less painful than expected. A smaller group were shocked or surprised at the sensation, and were worried that they had jumped and that the needle might have damaged the baby. A few found it very painful, using vivid imagery of being stabbed or punctured. However, even those who found it worse than expected felt it was worth the pain to get a definite diagnosis. Women identified a range of factors affecting their experience, including levels of anxiety, prior experience or knowledge of the procedures, levels of information provided, trust in the skill of the operator, or reassurance and empathy of the staff involved. CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: the needs of a small minority of women who find CVS or amniocentesis shocking and/or painful may be overlooked. A review of pre-test information and procedures is recommended to ensure that women are better prepared for possible physical sensations during the procedures to address the needs of this minority.