A case-control study was carried out using 84 cases of employee back injuries and 168 controls (matched triplets) at Children''s Hospital and Health Center, San Diego, (California, USA). The objective was to examine the impact of multiple individual and work-related risk factors for low-back injury from hospital employee health records. Hospital workers include occupational groups historically regarded as being at high risk, particularly nurses and others involved in patient care. In terms of tranditional risk factors, significant associations were found for history of low-back pain or "slipped disc" by self-report and for history of previous back injury. Working the day shift also was significant (odds ratio [OR] = 2.23, P < 0.005). Marital status (single) approached significance (OR = 1.65, confidence interval [Cl] = 0.091, 2.99), as did low body weight (OR = 1.47, Cl 0.70, 3.10). No significant association was found between cigarette smoking and low-back injury. Possible work site health promotion interventions to lower the risk of low-back injury in this population are suggested.