Anthropometric factors, spinal and limb-joint mobility, and trunk strength were measured in young students--55 men and 48 women (mean age 21.4 years, SD 1.6). Twenty-six of the men and 29 of the women had had back pain during the preceding year and they were compared with those without back pain. In the male back-pain group, extension, lateral flexion and the sum of mobility in the lumbar spine, and hip flexion and external rotation of the shoulders were significantly smaller. In the female back-pain group, extension and the sum of mobility in the thoracic spine, and extension, external rotation, and the sum of mobility in the hips were significantly diminished. Anthropometric factors and trunk strength had no significant relationship with a history of back pain except for a pronounced lordosis in women. The results suggest that ligamentous or capsular stiffness of the joints may be associated with low back pain in young adults.