Aim: Studying the possible influence of SNPs on efficacy and safety of calcineurin inhibitors upon heart transplantation. Materials & methods: In 60 heart transplant patients treated with tacrolimus or cyclosporine, we studied a panel of 36 SNPs correlated with a series of clinical parameters during the first post-transplantation year. Results: The presence of serious infections was correlated to ABCB1 rs1128503 (p = 0.012), CC genotype reduced the probability of infections being also associated with lower blood cyclosporine concentrations. Lower renal function levels were found in patients with rs9282564 AG (p = 0.003), related to higher blood cyclosporine blood levels. A tendency toward increased graft rejection (p = 0.05) was correlated to rs2066844 CC in NOD2/CARD15, a gene related to lymphocyte activation. Conclusion: Pharmacogenetics can help identify patients at increased risk of clinical complications. Original submitted 30 January 2015; revision submitted 27 March 2015