Basic randomized clinical trial (multicentre) in primary KTX to assess the safety and efficacy of a tac/rapa vs a tac/MMF regimen. Tac trough levels in accordance with current standards in both arms. Steroids to be used to individual centre protocol. Rapa trough levels will be adjusted to 5-10 ng/ml. Up to now only few data (primate and clinical) on tac/rap combinations available.