The expression of c-myc and p-ras-21 oncogenes was studied using an immunohistochemical method with monoclonal antibodies in 126 samples of gallbladder carcinoma (103 primary tumors and 23 metastatic lesions). Twenty five gallbladder samples without tumor evidence were used as controls. C-myc oncoprotein was positive in one control sample and p-ras-21 oncoprotein was negative in all. Among primary carcinomas c-myc was positive in 9 (9%) and p-ras-21 in 4 (4%); among metastatic carcinomas c-myc was positive in 6 (26%, p = 0,03 vs primary carcinoma) and p-ras-21 in 11 (48%, p < 0.001 vs primary carcinoma). There was a non significant association between c-myc and p -ras-21 expression and degree of histological differentiation and level of tumoral infiltration. It is concluded that c-myc and p-ras-21 oncoprotein expression is observed in less than 10% of primary gallbladder carcinomas and that this expression is significantly higher in metastatic carcinomas. This may reflect an activation or overexpression of these oncogenes in metastatic cells.