A major protein of M_r 68,000 with a previously described protein kinase activity (PK68), which is induced in HCMV-infected cells, is shown to be virus encoded by means of hybrid selection. The gene coding for the corresponding 4-kb mRNA was located within map units 0.510 and 0.525. This location is the same as that of pp65, a structural protein with no attributed function. The early nature of the protein was confirmed with its mRNA first appearing 3 hr after infection under cycloheximide reversal and phosphonoacetic acid blocking conditions. Another mRNA, 97 nucleotides smaller and 5′ coterminal with PK68, which codes for a M_r 52,000 protein, was also observed.