Objective: To determine the clinical effectiveness of the KTP/532 laser in treating endometriosis-associated infertility and to analyze the impact of additional infertility factors on outcome. Design: Prospective cohort analysis of 74 consecutive patients followed up to 24 months after surgery. Setting: Tertiary institutional infertility clinic. Main Outcome Measures: Cumulative pregnancy rates (PRs), monthly fecundity rates, monthly probability of pregnancy, crude PRs, and cure rates. Results: Thirty-eight percent (28) of patients conceived with a mean +/- SE time to conception of 7.2 +/- 0.8 months. The cure rates were 74% for the total patient sample, 51% for stage I, 69% for stage II, and 64% for stage III disease. Patients who had a cervical factor (P = 0.05), who underwent intrauterine insemination (P = 0.03), who received human menopausal gonadotropin (P = 0.03), or who had additional infertility factors (P = 0.02) had significantly lower crude PRs. The presence of additional infertility factors (P < 0.02) and intrafimbrial adhesions (P < 0.01) had a significant impact on cure rates. In the absence of additional factors, 60% (12) of patients with stage I and II conceived. When additional factors were excluded, the overall cure rate was 80%. Conclusion: The results indicate that the KTP/532 laser is an effective tool for the treatment of endometriosis-related infertility. The high prevalence of subtle adhesions may lend further impetus to operative laparoscopy for stage I and Il disease. Additional infertility factors may adversely affect outcome.