The presence of isolated epithelioid granulomata (EG) in the tissue samples of patients with malignant lymphomata (MT) has been related to a better prognosis. Miliary tuberculosis (MT) is frequent in Mexico (2.1 per 1000 patients at the Instituto Nacional de la Nutrición), where physicians dealing with the diagnostic and therapeutic approach of patients with ML and EG face the problem of differentiating the latter due to concurrent MT or to the neoplasm. Twenty-five patients with ML + MT and seven with ML + EG without MT were identified along 12 years; 32 ML patients matched according to age, sex, stage, type of ML and treatment were selected and their survival compared with that of the former groups. The prevalence of MT in ML patients was 35 times higher than that of the general population (P less than 0.001). Even though 6 and 18 month survival in patients with ML and MT or EG was higher than that of ML alone, differences are insignificant. It is concluded that the coexistence of MT and ML does not worsen the prognosis of ML; the high prevalence of MT in ML patients in selected countries could lead to the routinary administration of prophilactic antituberculous treatment.