The present study analyzed the health benefits data of employees in a southwestern United States manufacturing plant. The data consisted of the prevalence rates of headaches, muscle injuries, upper respiratory complaints, and colds/flu for baseline (1985) and intervention levels (1986-1988) for five high-risk jobs. The prevalence rates of headaches and muscle injuries decreased significantly (p < .001) from baseline levels for all five job groups. Comparisons with a nontreatment group revealed significant decreases (p < .05) for three of the five job groups. The findings support the efficacy of the ergonomic interventions. A health surveillance system is recommended for early detection and prevention of cumulative trauma disorders.