Background and aims: Hair entry into the midline is the generally accepted theory in pilonidal sinus formation. This theory is also involved in the pathogenesis of the recurrence after different types of operations for pilonidal sinus disease. The relationship of the suture lines and the midline was evaluated in this study. Patient and methods: Thirty-four patients with stage 4 or recurrent pilonidal sinus disease who underwent V - Y advancement flap closure were randomized into two groups: vertical suture line unrelated to midline (VLUM, n= 18) and vertical suture line related to midline (VLRM, n= 16). Results: None of the patients with or without a suction drain developed flap necrosis, local haematomas or seromas. The median length of the postoperative hospital stay was 3 days for the VLRM group and the VLUM group ( p> 0.05). The median follow-up period was 32 months. During the follow- up period, two recurrences were determined 22 and 15 months after operation in the VLRM group. Recurrences were situated in the scar tissue over the midline. Interpretation and conclusion: Routine application of suction drains is not recommended after V - Y advancement flap closure. Avoidance of the relationship of the postoperative suture line and the midline, if possible, offers a safe method of definitive reconstruction.