The objective of our investigation was to study isometric lifting strength in a population of industrial workers who perform a great variety of manual tasks, and to determine whether isometric strength is predictive of future back problems in such a population. Of 3,020 study subjects, 2,178 (72%) underwent strength testing in three standard lifting positions. During a 4-year follow-up period, 172 subjects tested reported back problems. When examining each isometric lift separately as a predictor of industrial back pain reports, those with greater isometric strength were at significantly greater risk than were weaker workers. However, after controlling for the effects of age, only a slight trend remained. For the blue collar workers in this study, isometric lifting strength testing was ineffective in identifying individuals at risk for industrial back problems.