The relationship between occupation and exposure to a number of occupational agents and lymphoid neoplasms was investigated in a case-control study of 69 cases of Hodgkin's disease, 153 non-Hodgkin's lymphomas, 110 multiple myelomas and 396 controls admitted for acute diseases to a network of teaching and general hospitals in the greater Milan area. Among the cases, there was a significant excess of individuals ever occupied in agriculture and food processing: the multivariate relative risks (RR) were 2.1 (95% confidence interval, CI = 1.0-3.8) for Hodgkin's disease, 1.9 (95% CI = 1.2-3.0) for non-Hodgkin's lymphomas and 2.0 (95% CI = 1.1-3.5) for multiple myeloma. Significant trends for duration of exposure to herbicides were observed for lymphomas, but the association was stronger for overall occupation in agriculture than with the specific question of herbicide use. History of occupation in the chemical industry was more frequent among Hodgkin's disease (RR = 4.3, 95% CI = 1.4-10.2), and a significant trend in risk was observed between duration of exposure to benzene and other solvents and multiple myeloma. No significant relation was found between any of the lymphoid neoplasms considered and rubber, dye, painting, printing, tanning leather, photography, pharmaceuticals, wood, coal/gas and nuclear industries.