BACKGROUND: Rhomboid excision with Limberg flap repair (RELIF) is an effective surgical procedure in pilonidal sinus disease (PSD) treatment. This study aimed to compare outcome of diathermy and scalpel in RELIF procedure in PSD surgery. METHODS: Patients undergoing RELIF procedure due to PSD at Adana Numune Training and Research Hospital between January 2012 and September 2012 were randomly assigned to diathermy (n=30) or scalpel (n=30) groups. The primary outcomes measured were duration of operation, drainage volume, postoperative numerical pain intensity scale (NPIS) scores, complications, duration of hospitalization length and time to return to daily activity. RESULTS: The mean age was 26.2 years (17-44 years). The mean operation duration was significantly lower in diathermy group (p=0.0001). Postoperative total NPIS score within the first 24 h was significantly lower in diathermy group (p=0.001). However, there were not any significant differences in term of NPIS scores in day 3 and day 7. There were no significant differences in terms of total drain output, drain removal time and length of hospital stay. There were no significant differences between groups in terms of duration to sit comfortably, return to daily activity and work. Recurrence of PSD was emerged in one patient in the diathermy group. CONCLUSION: Diathermy dissection in RELIF procedure in pilonidal sinus surgery is a safe technique and decreased operation time and postoperative pain. (NCT: ANEAH.EK.2012/21)