Objectives: Assess the efficacy of an outpatient-based interdisciplinary pain rehabilitation program for patients with active workers compensation claims. Patients: Data were available for 101 patients, primarily with chronic low back pain (75%), who participated in the program. Methods: Treatment included a 4-week (Monday to Friday), 8-hours/day graded progressive program that included individual and group therapies (pain psychology, physical therapy, occupational therapy, relaxation training/biofeedback, aerobic conditioning, pool therapy, vocational counseling, patient education and medical management). Outcome measures included program completion status, release-to-work status, return-to-work status, total scores on the Beck Depression Inventory, State-Trait Anxiety Inventory, Pain Catastrophizing Scale, and the McGill Pain Questionnaire Visual Analogue Scale (MPQ VAS). The majority of the patients (65%) graduated from the program. Pre-postoutcome data were available for those who graduated from the program. For noncompleters, last obtained MPQ VAS was compared with their initial MPQ VAS scores. Results: Of those completing the program, most patients (91%)were released to return to work; with 80% released to full-time status and 11% released to gradual return. Approximately half (49%) of the program completers returned to work. Paired-samples t-tests showed that program completers had significant reductions in depression (P=0.000), pain-related catastrophizing (P=0.033), and pain intensity (P=0.000), but not in anxiety (P=0.098). Interestingly, the last obtained (at early discharge/withdrawal) pain intensity scores (M=70.33) were higher than at baseline (M=61.20) in the noncompleters. This difference was not statistically significant (P=0.127) but may be clinically meaningful. Discussion: Our results support the efficacy of an outpatient-based 4-week interdisciplinary pain rehabilitation program in decreasing emotional distress, reducing pain intensity, and improving return-to-work status in the majority of completers in this challenging population. Patients reporting increased pain at discharge or those discharged early may have been due to operant factors.