BACKGROUND Urinary system fistula to the hip joint is a rare complication. We report a case of delayed posterior urethral fistula to the hip joint following penetrating gunshot wound injury. METHODS A 37-year-old Iranian Balochi male was shot with a firearm in the superior part of his right pelvis. He underwent primary closure on the same day. Ten months later, he developed urinary retention. He underwent retrograde urethrography and antegrade cystography which showed a stricture measuring 5 cm in length. There was also a history of progressive pain in the right hip joint accompanied by low grade fever which started 2 months after the initial injury. Hip X-ray showed evidence of an acetabular cavity and femoral head destruction diagnostic of complicated septic arthritis. The patient subsequently underwent reconstructive surgery for the urethral stricture and urethral fistula via a transperineal approach followed by total hip arthroplasty. CONCLUSIONS Hip joint contamination with urine following a urethro-acetabular fistula can lead to severe and disabling complications such as septic arthritis. We recommend that every clinician should keep these fistulas in mind as a complication of penetrating urethral injury and every attempt should be made for their early diagnosis and prompt treatment.