We sought to determine if conversion from tacrolimus/mycophenolate mofetil (TAC-MMF) to tacrolimus/mTOR inhibitor (TAC-mTOR) immunosuppression would reduce the incidences of BK and CMV viremia after kidney/pancreas (KP) transplantation. In this single center review, the TAC-mTOR cohort (n=39) was converted at one month post-transplant to an mTOR inhibitor and reduced dose tacrolimus. Outcomes were compared to a cohort of KP recipients (n=40) maintained on TAC-MMF. At 3-years post-transplant, KP survivals and incidences of kidney/pancreas rejection were equivalent between mTOR and MMF-treated cohorts. (p:ns). BK viremia-free survival was better for the mTOR versus MMF-treated group (p=0.004). In multi-variate analysis, MMF vs. mTOR immunosuppression was an independent risk factor for BK viremia (hazard ratio 12.27, p:0.02). Similarly, mTOR-treated recipients displayed better CMV infection-free survival compared to the MMF-treated cohort (p=0.01). MMF vs. mTOR immunosuppression (hazard ratio 18.77, p:0:001) and older recipient age (hazard ratio1.13 per year, p:0.006,) were independent risk factors for CMV viremia. Mean estimated GFR and HgbA1c levels were equivalent between groups at one, 2, and 3 years post-transplantation. Conversion from TAC/MMF to TAC/mTOR immunosuppression after KP transplantation reduced the incidences of BK and CMV viremia with an equivalent risk of acute rejection and similar renal/pancreas function. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.