We present the case of a 59-year-old woman who developed a major spontaneous retroperitoneal haematoma after performing a unilateral total hip arthroplasty. We reviewed the literature to see that a retroperitoneal haematoma is a rare event which can potentially be life-threatening.In our patient, the abdominal pain instead of being acute, as it happens on the majority of retroperitoneal haematomas, it started at day five postop associated to a sensation of abdominal fullness. An urgent CT was ordered to achieve de diagnose.A selective angiographic embolization was employed to stop the bleeding. Even if a total hip arthroplasty is a safe procedure, we need to be alert on operated patients with abdominal pain after the surgery and perform a careful evaluation.