The maximum isometric extensor muscle strength was measured in 10 healthy subjects of different combinations of hip and knee angles. An ordinary exercise device was used for the measurements and the method could be useful in clinical work. The results revealed that the knee angle does not affect the hip extensor strength. The highest extensor muscular moments occurred at 90 degrees hip flexion, decreasing with decreasing hip angle. The distribution of the strength over the motion sector differed between male and female. The weight of the body segments was found to utilize 10-24% of the maximum strength at hip angles 60 degrees-0 degrees with subjects in a prone position.