OBJECTIVES: To perform a cost-effectiveness analysis of Mycophenolate Sodium (MPS) vs Mycophenolate Mofetil (MMF) with empirical treatment of rejection, both options available at IMSS*. METHODS :A Decision Model was designed to analyze effectiveness and treatment cost of MPS and MMF for renal transplant patients. The outcome was renal graft survival related to gastrointestinal tolerance in the first year. The model starts with a renal transplant performed, in a period of three months the patient may experience gastric intolerance or tolerance. For the patients showing gastric intolerance, there are two alternatives: switching to azathioprine or reducing the dose of mycophenolates (MPS or MMF). Then, the patient moves to the next state which may be rejection (humoral or cellular) or not. The absorbent state is the graft losses which include the cost of the intervention of renal transplant plus the cost of replacement therapy: Ambulatory Peritoneal Dialysis (APD), Intermittent Peritoneal Mechanical Dialysis (IPMED), Intermittent Peritoneal Manual Dialysis (IPMAD) and Hemodialysis. A probabilistic sensitivity analysis (PSA) was performed using Monte Carlo technique. RESULTS :Annual patient costs of MMF were: $7,746.75, $7,993.03, $7,694.19 and $7,939.14 USD. For MPS were: $7, 673.35, $7,989.92, $7,605.80 and $7,920.64 USD with an incremental efficacy of 0.07 less graft rejection in APD, IPMED, IPMAD and hemodialysis respectively in one year horizon. PSA shows consistency on model results. CONCLUSIONS :MPS was a dominant alternative having lower costs and more effectiveness than MMF. These results show possibilities to achieve cost-savings and a potential clinical benefit in renal transplants, from the perspective of the Mexican public health system, in specific from IMSS. *IMSS (Mexican Institute of Social Security)