Cytomegalovirus (CMV) is one of the most common infections after solid organ transplantation. Improved assays to predict viral replication and disease would help refine current preventive strategies. Monitoring of CMV-specific T-cell responses may help guide clinical decision making. Several techniques are now available to quantify CMV-specific T-cell responses, including flow cytometry, enzyme-linked immunosorbent spot assay, and enzyme-linked immunosorbent assay. Standardization and validation of these assays have the potential to significantly change the monitoring and treatment of CMV and further personalize CMV prevention strategies. In this review, we discuss the measurement of CMV-specific T-cell responses and their clinical impact on the management of CMV after organ transplantation.