The relationship of low-back pain (LBP) to other diseases and to cardiovascular risk factors was studied in a random sample of 940 men from 40 to 47 years of age. The life-time incidence of LBP was 61%, the prevalence 31%. The prevalence of other diseases was the same as in previous studies in the same region. In a univariate analysis nine variables were found to be correlated to LBP; angina pectoris, calf pain, breathlessness on exertion, smoking, physical activity at work and during leisure time, worry and tension, fatigue at the end of the workday, and perception of stress. When the influence of other variables was assessed by analysis of covariance, four of the variables maintained a direct association with LBP, viz, calf pain on exertion, smoking, a high physical activity at work, and a frequent feeling of worry and tension.