There are conflicting reports regarding circulating leptin and its relationship between pregnancy outcomes in infertile women undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). We performed a systematic review and meta-analysis to assess the association between serum or follicular fluid (FF) leptin concentrations reported for infertile women and their IVF outcome. A systematic search was undertaken in available databases (PubMed, Scopus, Web of Science, The Cochrane Library and Embase) to find studies published up to Aug 2020 and the standardized mean difference with 95 % confidence interval was taken from 14 eligible studies. Both graphical (funnel plots) and test methods (Egger's regression test and the Begg) assessed the presence of publication bias. Subgroup analysis was used to investigate the source of heterogeneity. Pooled effect sizes based on the eligible papers indicated that of there is no statistically significant correlation between leptin levels in follicular fluid and serum on the day of ovum pick-up (OPU) and day of HCG (human chorionic gonadotrophin) administration in pregnant and non-pregnant women who underwent IVF/ICSI cycles. However, combination of leptin in serum and/or FF with other parameters may be a useful marker to predict IVF outcome.