The personnel at a geriatric hospital were randomized into two groups. One group was allowed to exercise during working hours to improve back muscle strength, endurance, and coordination. The other group did not participate in the exercise program and received no further advice or information. After 13 months, the training group had increased back muscle strength. One subject had been absent from work 28 days in the training group whereas 12 subjects had been absent 155 days from work because of low back pain in the control group (P < 0.004). The back pain complaints and intensity of back pain in the training group also decreased in a statistically significant way. Every hour spent by the physiotherapist on the training group reduced the work absence among the participants by 1.3 days, resulting in a cost/benefit ratio greater than 10.