Isometric and isokinetic muscle strength during right knee-extension and maximal extension velocity were measured in forty men and thirty-two women, regarded as representative for the healthy seventy-year-old urban population. Muscle strength in women was on average 56 percent of that in the men. Equations for calculation of normal values from the individual's body height and weight are given. The maximal extension velocity of knee-extension was similar in both sexes. The subjects were classified with regard to previous occupational and leisure-time physical activity. An inverse correlation was found between muscle strength and previous occupational physical activity in the men.