BACKGROUND The objective of this study was systematically to analyse published randomized trials comparing lightweight mesh (LWM) with heavyweight mesh (HWM) in open inguinal hernia repair. METHODS Randomized trials on LWM versus HWM were selected from the standard electronic databases. Reported outcomes were analysed systematically using RevMan. Pooled risk ratios were calculated for categorical outcomes, and mean differences for secondary continuous outcomes, using the fixed-effects and random-effects models for meta-analysis. RESULTS Nine randomized trials containing 2310 patients were included. There was significant heterogeneity among trials. There was no difference in duration of operation, postoperative pain, recurrence rate, testicular atrophy and time to return to work between LWM and HWM groups. The two mesh types had a similar risk of perioperative complications, but LWM was associated with a reduced risk of developing chronic groin pain (risk ratio (RR) 0·61, 95 per cent confidence interval 0·50 to 0·74) and a reduced risk of developing other groin symptoms, such as stiffness and foreign body sensations (RR 0·64, 0·50 to 0·81). CONCLUSION The use of LWM for open inguinal hernia repair was not associated with an increased risk of hernia recurrence. LWM reduced the incidence of chronic groin pain as well as the risk of developing other groin symptoms.