OBJECTIVE: Optimal surgical treatment for chronic pilonidal sinus (PS) disease should be easy and efficient. The purpose of this study was to establish the feasibility of and results after ambulatory simple midline excision and primary wound closure under local anaesthesia. PATIENTS AND METHODS: The prospective nonrandomised single institution study included 131 consecutive PS patients admitted for surgery. After standardized surgery, all patients were prospectively followed until fully healed. Complications were registered. Results after 41 months (mean, range 36-59) were evaluated by questionnaire. RESULTS: 95% were primary closed. All were ambulatory treated and 98% under local anaesthesia. 88% healed in two weeks. 5.6% exhibited minor wound healing defects and 6.4% demanded full debridement of the wound. Mean delayed healing time was 7.5 weeks (range 3-12). 8% developed a recurrence. 10% of the remainders reported a slight tenderness in the scar area. 90% were symptom-free. CONCLUSION: PS treatment as of above is readily achieved. Wound related complications were reasonably few and in the same magnitude as after more complex excision techniques and induced no significant long-term sequels. Recurrences could, however, be more common. Prospective randomised studies are warranted to determine if there are any significant differences between excision techniques in and out of the midline.