Male patient, age 32 years, intensive recreational athlete (triathlon, mountain climbing) with left hip pain in flexion and rotational movements. Clinical examination demonstrates a restriction of internal rotation in flexion above 90° associated with pain (anterior impingement). The radiograph demonstrates a FAI with a cam deformity and joint space narrowing in the peripheral joint area (3a–3c). The MRI showed a chondrolabral lesion and acetabular subchondral cyst (3d). Considering his young age and his rejection to a THR a hip arthroscopy was performed. Full-thickness chondral damage in acetabulum (3e) and diffuse fibrillation of cartilage in femoral head was found during the arthroscopy (3f). These should be considered an advanced osteoarthritis finding with a very unpredictable clinical outcome. The radiography one year later shows the progression of the chondral damage of the hip (3g). This case shows that with hip arthroscopy a temporary relief of pain can be achieved in cases of advanced chondral damage but it cannot change the course of the disease and progression to osteoarthritis of the hip.