Percutaneous endoscopic lumbar discectomy (PELD) is one of the surgical options for soft lumbar disk herniation, but the learning curve is perceived to be steep. The first 51 PELD cases performed for single-level intracanalicular lumbar disk herniation causing radiculopathy by the same surgeon were prospectively studied. The patients were divided into 3 groups of 17 patients, and the PELD learning curve was assessed by evaluating operating time, failure rate, complication rate, and 1-year reherniation rate. One-year clinical success rate was assessed by telephone interviews. The herniated disk was successfully removed by PELD in 47 patients. Four patients required subsequent open discectomy due to PELD failure. There were 2 minor complications. One year after surgery, clinical success was achieved in 42 of the 47 patients in whom PELD was initially successful, and reherniation developed in 5 patients. A significant reduction in operating time was observed after 17 patients had been treated (p = 0.0004). No significant differences were observed in terms of either failure rate or complication rate between the 3 groups. No significant differences were observed in terms of either the clinical success rate or the reherniation rate at 1 year after surgery. The PELD learning curve seems to be stable and acceptable with proper pre-PELD training.