A substantive amendment to this systematic review was last made on 22 June 1999. Cochrane reviews are regularly checked and updated if necessary.ABSTRACT Background and objectives: The original cups used for vacuum extraction delivery of the fetus were rigid metal cups. Subsequently, soft cups of flexible materials such as silicone rubber or plastic were introduced. Soft cups are thought to have a poorer success rate than metal cups. However, they may be less likely to be associated with scalp trauma, easier to apply and less likely to injure the mother. The objective of this review was to assess the effects of soft versus rigid vacuum extractor cups on perineal injury, fetal scalp injury, short and long term pain and success rate. Search strategy: We searched the Cochrane Pregnancy and Childbirth Group trials register. Selection criteria: Acceptably controlled comparisons of soft versus rigid vacuum extractor cups. Data collection and analysis: Two reviewers assessed trial quality and extracted data. Study authors were contacted for additional information. Main results: Nine trials involving 1375 women were included. The trials were of average quality. Soft cups are significantly more likely to fail to achieve vaginal delivery (odds ratio 1.65, 95% confidence interval 1.19–2.29). However, they were associated with less scalp injury (odds ratio 0.45, 95% confidence interval 0.15–0.60). There was no difference between the two groups in terms of maternal injury. Reviewers' conclusions: Metal cups appear to be more suitable for “occipito‐posterior,” transverse and difficult “occipito‐anterior” position deliveries. The soft cups seem to be appropriate for straightforward deliveries. Citation: Johanson RB, Menon BKV. Soft versus rigid vacuum extractor cups for assisted vaginal delivery (Cochrane Review). In: The Cochrane Library, Issue 4, 1999. Oxford: Update Software.••• The preceding reports are abstracts of regularly updated, systematic reviews prepared and maintained by the Cochrane Collaboration. The full texts of the reviews are available in The Cochrane Library (ISSN 1464–780X). See http://www.update‐software.com/cochrane.htm, or contact Update Software,info@update.co.uk, for information on subscribing to The Cochrane Library in your area.Update Software Ltd., Summertown Pavilion, Middle Way, Oxford OX2 7LG, United Kingdom (Tel.: + 44 1865 513902; Fax: + 44 1865 516918).