Recurrence of pilonidal sinus disease after surgical intervention is not a very rare problem although sophisticated reconstruction procedures have been developed. Recurrence is thought to be related to the anatomical status of the patients, i.e., depth of the intergluteal groove. Obese patients have deeper intergluteal grooves. The aim of this study was to use body mass index (BMI) as an objective indicator of obesity to determine whether there is a relationship between BMI and recurrence of pilonidal sinus disease. BMI was calculated preoperatively in 114 patients with pilonidal sinus disease who were treated by excision and Limberg flap transposition between 1996-1999 in general surgery departments of two university hospital clinics. Fifteen patients were referred to our clinics after surgical intervention carried out at other institutions. Their average BMI was calculated by using their hospital records. The mean follow-up period was 24 months (range 10-36). Six of the 114 patients (5%) had recurrence. The mean BMI of patients with and without recurrence was 29.35 and 27.415, respectively (P<0.05). The mean BMI of 15 patients referred to us because of recurrent disease was 29.41; however, that of patients with primary pilonidal sinus disease was 27.212 (P<0.05). Their BMI before their first operation was 29.30. This was also significantly higher than patients with primary disease (P<0.05). We conclude that obese patients with high BMI have a higher risk of recurrence of pilonidal sinus disease after surgical intervention.