AIMS: The purpose of this study was to evaluate excision and open granulation versus excision and primary closure as treatments for pilonidal sinus. SUBJECTS AND METHODS: We evaluated a group of 141 patients operated on for a pilonidal sinus between 1991 and 1995. Ninety patients were treated by excision and open granulation, 34 patients by excision and primary closure and 17 patients by incision and drainage, as a unique treatment of an infected pilonidal sinus. RESULTS: The first group, receiving treatment of excision and open granulation, experienced the following outcomes: average length of hospital stay, four days; average healing time; 72 days; average number of post-operative ambulatory visits, 40; average off-work delay, 38 days; and average follow-up time, 43 months. There were five recurrences (6%) in this group during the follow-up period. For the second group treated by excision and primary closure, the corresponding outcome measurements were as follows: average length of hospital stay, four days; average healing time, 23 days; primary healing failure rate, 9%; average number of post-operative ambulatory visits, 6; average off-work delay, 21 days. The average follow-up time was 34 months, and two recurrences (6%) were observed during the follow-up period. In the third group, seventeen patients benefited from an incision and drainage as unique treatment. The mean follow-up was 37 months. Five recurrences (29%) were noticed, requiring a new operation in all the cases. DISCUSSION AND CONCLUSION: This series of 141 patients is too limited to permit final conclusions to be drawn concerning significant advantages of one form of treatment compared to the other. Nevertheless, primary closure offers the advantages of quicker healing time, fewer post-operative visits and shorter time off work. When a primary closure can be carried out, it should be routinely considered for socioeconomical and comfort reasons.