Observations on transverse sections of whole tibialis anterior, triceps and soleus muscles obtained soon after death from 3 previously normal individuals aged 5, 8 and 19 years respectively who had died of head injury have shown that utilising histochemical methods for demonstrating succinic dehydrogenase can successfully distinguish histochemical Type I, Type II and intermediate fibres even after death. These observations have shown that in triceps and tibialis anterior the Type I and Type II fibres appear to be randomly distributed throughout the muscle and there is no selective pattern of distribution dependent upon the part of the muscle from which sections are taken, and no concentration of any particular histochemical type in any single area. In the soleus muscle, it was, however, found that no fibres of histochemical Type II were present, that Type I fibres predominated but that some of intermediate histochemical type were also to be found. © 1969.