The purpose of this study was to examine the association between maximal isometric strength and mobility among 75-year-old men and women. All those born in 1914 and resident in the city of Jyväskylä in August 1989 comprised the study group (n = 388); 355 persons were interviewed at their homes (92%): 101 men (81% of all male residents) and 186 women (75%) participated in the laboratory strength tests. As part of the home interview the person's mobility at home, on stairs and outdoors was assessed using a four-point scale:--1 able, 2--able with difficulty, 3--needs help, 4--unable. Poor mobility was more common among the drop-outs than among the strength-tested subjects in both sexes. Maximal isometric strength of hand grip, arm flexion, knee extension and trunk flexion and extension were measured using specially constructed dynamometers. The strength results were adjusted for body weight. The study also included a stair-mounting test and measurement of maximal walking speed. The body-weight adjusted maximal forces were consistently significantly associated with mobility. Those who claimed no problems in the mobility interview and performed better in the walking and stair-mounting tests exhibited greater maximal isometric strength. The present results indicate that maximal isometric strength tests provide useful information about physical functional capacity among elderly people. These findings also suggest that the maintenance of adequate strength could be favourable to the mobility of older persons.