The first five cases of endomyocardial fibrosis to be reported from Mozambique are described in an autopsy series over the years 1975-77, together with 85 cases of rheumatic heart disease in patients who died and were autopsied during the same period. Outside the central parts of the African continent, endomyocardial fibrosis does not seem as rare as previously thought. Observations on the age and sex of the patients correspond with what is already known about both diseases. The strikingly higher frequency of rheumatic heart disease discussed in this review is at variance with the findings of SHAPER et al. in Uganda over the years 1950-65 and poses problems as to the hypothesis of a common aetiological process in both diseases, i.e. a hypersensitivity mechanism acting on cardiac connective tissue.