Abstract: We have developed a novel diagnostic technology to monitor the human cytomegalovirus (HCMV)‐specific CD8+ T‐cell responses that is based on the detection of secreted interferon‐gamma (IFN‐γ) in the whole blood (referred to as QuantiFERON^®‐CMV). Evaluation of QuantiFERON^®‐CMV in healthy individuals revealed that this technology was at least as sensitive and with some HCMV epitopes more sensitive than the ELISPOT for detecting ex vivo IFN‐γ. Results from QuantiFERON^®‐CMV assays showed 97% (36/37 individuals) agreement with the anti‐HCMV serology test in healthy individuals. Furthermore, we also show that this technology can be used to assess HCMV‐specific T‐cell responses in transplant patients. This study shows that QuantiFERON^®‐CMV is a simple, reproducible, and reliable test for the detection of IFN‐γ in response to HCMV CD8+ T‐cell epitopes, and may be a valuable diagnostic test for the detection of HCMV infection and a useful clinical tool for monitoring the immune response in immunosuppressed patients during therapy.