We analyzed 104 patients with non-Hodgkin's lymphoma, follicular or diffuse large-B-cell-type lymphoma, in order to evaluate the correlation between clinical characteristics and immunohistochemical parameters. Immunostaining was performed by means of monoclonal antibodies against Ki-67, bcl-2, and p53 expression. Forty-nine of the patients showed follicular lymphoma. A high expression of bcl-2 was found in 93%, high expression of p53 in 57%, and low expression of Ki-67 in 96%. Follicular lymphoma grade III showed a p53 expression (p = 0.07) slightly higher than follicular lymphoma grades I and II, not reaching statistical significance. Follicular lymphoma grades I and II tended to express lower Ki-67 and higher levels of bcl-2 expression than grade III (p = 0.06). Fifty-five cases showed diffuse large-B-cell lymphoma. Among them, bcl-2 was absent in 39%, whereas p53 and Ki-67 expression were high in 38%. In the diffuse large-B-cell lymphomas, a high bcl-2 expression correlated with stages III and IV (p = 0.03) and involvement of more than one extranodal area (p = 0.03). High Ki-67 expression was also associated to extranodal involvement of more than one area (p = 0.03). Overall survival of patients did not show statistically significant differences regarding Ki-67, bcl-2, and p53 tumoral expression. Prognostic factors for overall survival in the multivariate analysis were age (p = 0.02) and LDH (p = 0.003). Time to progression was worse among follicular lymphoma with high p53 expression than with mild/moderate p53 expression (p = 0.009).