Mycophenolate mofetil had no effect on fertility of male rats at oral doses up to 20 mg kg-1 day-1. The systemic exposure at this dose represents 2-3 times the clinical exposure at the recommended clinical dose of 2 g/ day in renal transplant patients and 1.3-2 times the clinical exposure at the recommended clinical dose of 3 g/ day in cardiac transplant patients.