At present, it is unclear what the role is of laparoscopic ovarian diathermy (LOD) and of metformin administration as second-line treatments for ovulation induction in women with polycystic ovary syndrome (PCOS) after failure of clomiphene citrate (CC) treatment. The aim of the present study was to compare in a randomized double-blind placebo-controlled fashion the effectiveness of LOD with metformin administration in the treatment of CC-resistant women with PCOS. A total of 120 overweight primary infertile anovulatory CC-resistant women with PCOS were enrolled and randomized into two groups of treatment. Group A underwent diagnostic laparoscopy, whereas group B underwent LOD. At hospital discharge, the patients were treated for 6 months with metformin cloridrate (group A; 850 mg twice daily) or with multivitamins (group B). The ovulation, pregnancy, abortion, and live-birth rates were evaluated. At the end of the study, the total ovulation rate was not statistically different between both treatment groups (54.8 vs. 53.2% [correction] in groups A and B, respectively), whereas the pregnancy (21.8 [correction] vs. 13.4%), the abortion (9.3 [correction] vs. 29.0%), and the live-birth (86.0 [correction] vs. 64.5%) rates were significantly (P < 0.05) different between the two groups. Our data show that metformin administration is more effective than LOD in overall reproductive outcomes in overweight infertile CC-resistant women with PCOS.