BACKGROUND: Total knee arthroplasty (TKA) generates severe postoperative pain in 60% of patients and moderate pain in 30% of patients. Because inadequate postoperative pain control can hinder early physiotherapy and rehabilitation, it is the most influential factor dictating a good outcome. The purpose of this study was to evaluate the effectiveness of continuous psoas compartment block (PCB) in comparison to intravenous patient-controlled analgesia (IVPCA) in TKA patients. METHODS: 40 TKA patients were randomly divided into 2 groups. Group IVPCA (n = 20) received intravenous patient controlled analgesia (IVPCA) for 48 hours. Group PCB (n = 20) received continuous PCB for 48 hours at the fourth intertransverse process of the lumbar using the C-arm. Pain scores, side effects, satisfaction, the length of hospital stay, rescue antiemetics, and analgesics were recorded. RESULTS: Pain scores (VNRS 0-100) were higher in Group IVPCA than in Group PCB. Nausea and sedation occurred more frequently in Group IVPCA than in Group PCB. There were no differences between the groups in the length of the hospital stay, satisfaction scores, and the use of rescue antiemetics and analgesics. CONCLUSIONS: Continuous PCB seemed to be an appropriate and reliable technique for TKA patients, because it provided better analgesia and fewer side effects such as nausea and sedation when compared to IVPCA.