In order to analyse the efficacy of resection/ablation of minimal/mild endometriotic lesions for improving fertility, we conducted a randomized clinical trial. Eligible patients were women aged </=36 years who were trying to conceive and had a laparoscopically confirmed diagnosis of minimal/mild endometriosis (stage I or II of the revised American Fertility Society classification) and otherwise unexplained infertility for >/=2 years. Eligible women were randomly assigned to resection or ablation of visible endometriosis (54 patients) or diagnostic laparoscopy only (47 patients). After laparoscopy women tried to conceive spontaneously for 1 year (follow-up period). A total of five women withdrew from the study: three for personal reasons, and two were lost to follow-up. Considering 51 women in the resection/ablation and 45 in the no-treatment group who ended the follow-up period, 12 (24%) in the resection/ablation group and 13 (29%) in the no treatment group conceived; the difference was not significant. Two spontaneous abortions were observed in the resection/ablation group and three in the no-treatment one. Thus the 1 year birth rate was 10 out of 51 women (19.6%) in the resection/ablation group and 10 out of 45 women (22.2%) in the no-treatment group. In conclusion, the results of this study do not support the hypothesis that ablation of endometriotic lesions markedly improves fertility rates.