['Current assays and tests that are used to determine the degree of immunosuppression in renal transplant recipients are suboptimal. The ImmuKnow assay (Cylex), a measure of intracellular CD4+ T cell ATP release proposed as a means to quantify cell-mediated immunity in transplant recipients, could be considered as a potential tool to identify patients at risk for opportunistic infections (OI) or acute rejection (AR).', 'We retrospectively analyzed 1330 ImmuKnow assay values in 583 renal transplant recipients at a single center from 2004 to 2009 and correlated these values with episodes of OI and AR in the subsequent 90 days. Assay values were compared with a control population matched for age, gender, and time post-transplantation.', 'In patients with OI (n=94), there were no differences in prior mean assay values compared with matched controls (386 versus 417 ng/ml, P=0.24). In 47 patients with AR, again no differences were detected in prior assay results (390 versus 432 ng/ml, P=0.25) when compared with controls. "Low" values (≤225 ng/ml) lacked sensitivity and specificity as a predictive test for subsequent OI, as did "strong" (≥525 ng/ml) values as a predictive test for subsequent AR.'] Does single time point immune function assay ( ImmuKnow ) testing aid in the prediction of future opportunistic infections or acute rejection?