Psoas muscle hematoma is defined as a spontaneous or traumatic retroperitoneal collection of blood involving the psoas muscle. Early symptoms of an iliopsoas hematoma include lower abdominal or severe groin pain. Although psoas hematoma is a known complication of coagulopathy, psoas hematoma caused by non-penetrating trauma is the subject of only scattered reports and its significance has not been well described in the literature, so the aim of this study was to report a case of blunt traumatic psoas hematoma with the fracture of vertebral transverse process with the presentation of gross hematuria. A 65-year-old Iranian man slipped backward to the ground, and the patient complaint of gross hematuria and difficulty in walking. There was severe left costo-vertebral angle (CVA) tenderness, and mild groin tenderness, and the lower back area was painful, and he had some pain with the flexion of the vertebral column, and there was tenderness on lumbar spine, but there was no tingling, paresthesia, and weakness in left lower extremity. Hip flexion was 3/5 in the left lower. We used some diagnostic modalities as x-ray radiography, ultrasonography, computed tomography (CT) scan with intravenous (IV) contrast, CT cystography, and intravenous pyelogram (IVP) IVP to differentiate the diagnoses and also find skeletal and other organ injuries associated with this kind of injury. We can conclude that post-traumatic psoas hematoma is a rare condition. The diagnostic modality of choice is CT scan which allows rapid identification and measurement of the hematoma. The lesion usually treated with non-operative conservative management.