During 1981-85, 1084 cases of benign breast lesions were seen at Kenyatta National Hospital, Nairobi, Kenya. In the same period, 417 cases of breast carcinoma were diagnosed. Amongst the benign lesions fibroadenoma was the most common diagnosis (531 cases) followed by mastopathy (177 cases). The incidence rate of fibroadenoma was 1.6 per 100,000 person-years. Classic tubular adenoma was seen in 26 cases and in 26 cases a mixture of fibroadenoma and tubular adenoma was seen. These findings suggest that breast adenoma is probably one tumour with different expressions of the glandular and fibrous areas. We found no specific gross or microscopical features by which it was possible with certainty to distinguish between fibroadenoma and giant fibroadenoma and therefore suggest that the term giant fibroadenoma be avoided. The histopathologic pattern of mastopathy showed great variation, but the lesions were without difficulty divided into three main categories, i.e. cystic, fibrous and hyperplastic mastopathy. This distinction is important as cases with marked epithelial hyperplasia have been shown to have an increased cancer risk. Except for low parity no similarities in risk factors for mastopathy and breast cancer have been shown so far.