We evaluate 5-year results of a prospective randomized trial that compared cyclosporine microemulsion (CsA-me) and Tacrolimus (Tac) for primary immunosuppression. One hundred one adult patients undergoing liver transplantation were randomized to receive Tac (n = 50) or CsA-me (n = 51). The most frequent indication for the procedure was cirrhosis due to virus C followed by alcoholism. Survival rates at 1, 3, and 5 years were 86%, 75%, and 72%, respectively; there was no significant difference between CsA-me versus Tac arms. Acute rejection occurred in 30 cases (30%), independent of the type of primary immunosuppression. Serious adverse events were reported significantly more among patients under CsA-me (48 episodes) than under Tac (32 episodes). Nineteen patients were switched to the other calcineurin inhibitor. The switch was much more frequent from CsA-me to Tac (n = 15; 29.4%), mainly because of lack of efficacy (n = 10; 19.6%). There were no cases of chronic rejections in the Tac arm. Four patients were switched from Tac to CsA-me for side effects; only 1 remains alive, after treatment was changed from CsA-me to an antimetabolite. There were no statistical differences in renal dysfunction, diabetes, hypertension, neurologic disorders, new-onset malignancies, or infections. There were no differences in survival or rejection among the intention-to-treat groups. Serious adverse events, total patients with switch of calcineurin inhibitor, as well as switches due to lack of efficacy, were statistically more frequent under CsA-me. Tacrolimus seems to be a more appropriate drug to be used for primary immunosuppression in liver transplantation.