The psoas abscess is an entity, sometimes forgotten in our daily practice, because of infrequency and difficulties in diagnosis. Primary psoas abscess is very rare and gram-positive micro-organisms account for more than 80% of the cases. Our case, a 62-year-old man was admitted with a 5-year history of back pain and fever. Physical examination was normal, except a palpable hepatomegaly with a mild tenderness over his lower right abdominal quadrant. The Brucella agglutination test was strongly positive with a titre of 1/640, as Rose Bengal Spot test. Blood cultures for brucella were positive on the fourth day and became negative, as the specific therapy started. Further examination with ultrasonography and computed tomography revealed an abscess of 40 + 75 rum in the psoas muscle. Complete resolution of symptoms achieved within 6 weeks. Although clinical presentation of psoas abscesses is often similar and non-specific, early aetiological diagnosis is extremely important, because of high achievement with appropriate antibiotic regimens. Brucellar psoas abscess seems very rare even in Turkey, where Brucella is still highly endemic. Such a case has not been previously reported from Turkey, as far as we know.