Primary retroperitoneal abscess complicated with septic arthritis of the hip is an unusual disease. The insidious and occult nature of abscess coexistent with arthritis causes diagnostic delays, prolonged sepsis, and considerably higher morbidity and mortality. We herein present a case of gouty arthritis and avascular necrosis of the femoral head in a 41-year-old woman who complained of fever, right flank pain, body weight loss, swelling over her right lower limb, and 2 weeks of pain in the right hip. The computed tomographic scan showed a huge abscess (about 32 x 10 x 8 cm) over the right posterior pararenal space, with swelling of the right psoas, iliac, and obturator muscles. During surgery, the abscess was drained and sequestrectomy of the right hip was performed. Cultures of pus from the retroperitoneum and right hip showed Escherichia coil and Staphylococcus aureus. We review the literature and discuss possible causes.