This retrospective study on 545 primary mammary carcinomas shows highly significant negative correlations between the presence of oestrogen and progesterone receptors on the one hand and nuclear grading, degree of necrosis or of inflammatory infiltration and histological grading on the other hand. The relationship between receptors and histological grading is not as highly significant as reported by others because of the criteria of grading that were selected. All these correlations disappear when only premenopausal patients are considered. Receptors are most frequently positive in tubular and lobular carcinomas but are rarely found in medullary carcinoma. The presence of receptors bears no link with the size of the tumour. When a tumour is too small for both, histopathological and biochemical analysis to be performed, it is possible to predict the existence of positive receptors thanks to histological criteria of tumour differentiation with a probability of 75% for 67% of patients.