BACKGROUND: Physical conditioning programs, variously called work conditioning, work hardening and functional restoration/exercise programs, aim to improve work status and function. Previous attempts have been made to evaluate the efficacy of work-oriented back pain management programs, but none have focused exclusively on work or functional outcomes. OBJECTIVES: To compare the effectiveness of physical conditioning programs with management strategies that do not include physical conditioning programs, for workers with back and neck pain, in reducing time lost from work and increasing functional status. SEARCH STRATEGY: We searched the following databases to 31 May 2000: MEDLINE from 1966, EMBASE from 1980, CINAHL from 1982, Biomedical Collection: I (from 1993), II (from 1995), III (from 1995), IV (from 1995), PsycINFO from 1967, the Cochrane Central Register of Controlled Trials, PEDro. SELECTION CRITERIA: Randomized controlled trials (RCTs) that studied adults with work disability related to back or neck pain, who were included in physical conditioning programs. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and assessed trial quality. Where data could be pooled, a meta-analysis was performed using RevMan. For continuous outcomes, we nominated a saving of 10 sick days as the smallest treatment effect that would be clinically worthwhile. For dichotomous outcomes, we considered that an intervention that affected less than one in 10 people would not be clinically worthwhile. MAIN RESULTS: Eighteen RCTs were identified in 20 publications. Twenty-three relevant contrasts were investigated. There is evidence that physical conditioning programs that include a cognitive-behavioural approach can reduce the number of sick days lost at 12 months follow-up by an average of 45 days, when compared to general practitioner usual care or advice, for workers with chronic back pain. For work-related outcomes, there is little evidence for or against the efficacy of specific exercises that are not accompanied by a cognitive-behavioural approach, in reducing sick days lost due to back pain, for workers with either acute or chronic back pain. REVIEWER'S CONCLUSIONS: Physical conditioning programs that include a cognitive-behavioural approach plus intensive physical training (specific to the job or not) that includes aerobic capacity, muscle strength and endurance, and coordination; are in some way work-related; and are given and supervised by a physiotherapist or a multidisciplinary team, seem to be effective in reducing the number of sick days for some workers with chronic back pain, when compared to usual care. However, there is no evidence of their efficacy for acute back pain.