Aim: To report on the clinical features, diagnosis, and treatment of psoas abscess (PA) with special attention to the presence of septic shock. Patients and Methods: This study included 17 patients (mean age 66.2, range 43–81 years) with PA. Treatment consisted of intravenous administration of antibiotics and abscess drainage, either surgical or percutaneous with ultrasound guidance. Results: The typical patients presented with fever >38°C (16/17, 94%), pain in back, flank, or abdomen (15/17, 88%), hip flexion contracture with pain extension (14/17, 82%), and mass felt in the flank (5/17, 29%). All 8 patients without septic shock (100%) had the clinical triad (fever, pain in back, flank, or abdomen, and hip flexion contracture) as compared with 4 of 9 patients with septic shock (44%) (p = 0.012). The duration of symptoms before hospitalization was significantly shorter in the patients with septic shock (median 2, range 1–5 days) than in those without septic shock (median 18.5, range 11–63 days; (p = 0.0005). The mortality rates were 33% (3 of 9) and 0% (0 of 8) in the patients with and without septic shock, respectively (p = 0.071). Conclusions: PA patients with septic shock had a tendency to have nonspecific symptoms and an occult clinical course as compared with those without septic shock. A delay in diagnosis and treatment can result in a worse clinical outcome (death or totally disabled state). Increased awareness of this condition should lead to earlier diagnosis and treatment with improved outcomes.