Two muscles involved in locomotion the vastus lateralis and the gastrocnemius, were compared on a variety of histochemical an biochemical properties. Ten active males, age 20 - 24 years, served as subjects. Fibre type distributions, type I, type IIA and type IIB, as determined from samples extracted by muscle biopsy were similar in both muscles. In addition, no significant difference (p greater than 0.05) was found between fibre types in each muscle for fibre size, relative area, capillaries per fibre and the ratio of capillaries per fibre area. The activities of a number of enzymes representative of energy supplying pathways - the citric acid cycle (succinate dehydrogenase, SHD; beta-hydroxyacyl CoA dehydrogenase, HADH), glycogenolysis (total phosphorylase, PHOSP), glycolysis (phosphofructokinase, PFK) - were of similar magnitude between the two muscles. The only exception noted was for the activity of a glycolytic enzyme, lactate dehydrogenase, LDH, where a 16% higher value was observed in the vastus lateralis. The close degree of homogeneity displayed between these two muscles may be of significance in providing for a functional synchrony to occur in locomotor activities of varying intensity.