The trial compares excision in the midline at surgery for pilonidal disease versus excision lateral of the midline (Karydakis operation) at surgery for pilonidal disease by randomly allocating patients with pilonidal disease to two groups of surgeons, each group being trained for one of the two methods.

Excision in the midline and primary suture is a long proven method of treating pilonidal sinus. However it's associated with high incidence of post operative infection and recurrence. On the other hand Karydakis operation (excision lateral of the midline, transposition flap and primary suture) is just a slightly more complicated procedure but has five times less recurrences reported in case series. The purpose of the present study is to compare the surgical results and costs of the two surgical methods utilized. In addition the investigators aim to compare the quality of life at defined time points after surgery. Eligible patients are randomized to two groups of surgeons, well trained in either the midline operation or the Karydakis operation (expertise based design). The design of the study allows wide inclusion criteria for participants, a cost-utility approach in the analysis, and a high external validity of the conclusions reached.

Comparison: Midline excision andd primary suture compared with the Karydakis operation (excision lateral of the midline and primary suture) for pilonidal disease.

Inclusion Criteria:

• Age 18 years or older.
• Surgery is considered the best available treatment.
• The patient understands trial information and is capable of making a decision for informed consent after having received information.
• The patient wants to undergo surgery for pilonidal sinus and accepts participation in the trial.

Exclusion Criteria:

• Patient has had a pilonidal abscess during the last four weeks before the planned day of surgery
• Patient has had surgery (excision) for pilonidal sinus more than once before.