Objectives:The aim of this study was to assess the safety and clinical outcome of Helica thermal coagulation (TC) for the treatment of pelvic pain symptoms and infertility caused by early endometriosis. Materials and Methods: A prospective, observational study was conducted at a secondary health care hospital in Cumbria, United Kingdom. Forty-three (43) women, with either pelvic pain symptoms, infertility, or both and diagnosed with minimal or mild endometriosis at laparoscopy, were included in the study. Eleven (11) women complained of pelvic pain symptoms only and 18 had infertility only, whereas 14 complained of both. All women were treated on a day-case basis. The revised American Fertility Society classification was used to stage endometriosis. Laparoscopic Helica TC was used to ablate all visible endometriotic spots. Relief of pelvic pain symptoms and conception were assessed up to 6 months after the procedure. Complications occurring during or after the procedure were recorded. Results: All women completed the study up to 6 months of follow-up. Eighteen (18) of 25 (18/25) women (72%) had satisfactory relief of pelvic pain symptoms at 6 months. The cumulative pregnancy rate was 34% (11/32). Six (6) pregnancies were spontaneous and occurred 1 month after the procedure, whereas 5 pregnancies were recorded at 3-6 months. No surgical complications were encountered. Conclusions: Conservative laparoscopic surgery using Helica TC is simple, very safe, and effective at relieving pelvic pain symptoms and improving fertility in women with early-stage endometriosis. Large, randomized, controlled trials on the efficacy of this procedure are needed. (J GYNECOL SURG 23:45)