Patients with developmental dysplasia of the hip may present with acetabular rim overloading, labral hypertrophy, and tear. Our hypothesis was that isolated arthroscopic treatment of labral tear is likely to fail in most patients. We investigated 34 patients who underwent at least one arthroscopy of the hip for labral tear. Developmental hip dysplasia or other morphologic abnormalities of the hip were confirmed in all patients. Arthroscopy failed to relieve pain in 24 patients. We observed accelerated arthritis in 14 patients and migration of the femoral head in 13 patients. Sixteen patients underwent further surgery (further surgeries included periacetabular osteotomy [6 patients], femoroacetabular osteoplasty [7 patients], and total hip arthroplasty [3 patients]). At the latest follow-up, all patients but one were pain-free. Patients with evidence of abnormal hip morphologies may not benefit from hip arthroscopy and isolated treatment of the labrum; in fact, the latter may accelerate the process of arthritis in some patients.