Polyadenylated transcripts of a monkey lymphotropic papovavirus (LPV), which can be propagated in monkey and human lymphoblastoid cell lines, were identified and mapped. Polyadenylated RNA was purified from cells of the human line BJA/B infected with LPV, and was hybridized with various LPV DNA fragments. The hybrids were treated with S1 endonuclease and analyzed by alkaline gel electrophoresis. This analysis revealed two groups of RNA molecules encoded in two regions of the LPV genome. One group includes four colinear transcripts of 2.3, 2.1, 1.85, and 1.2 kb, whose polyadenylated termini map at a single site on the LPV DNA. The second group includes two less-abundant transcripts of 1.8 and 1.95 kb. The polarities of the LPV transcripts were determined by hybridizing cDNA complementary to their 3' termini with LPV DNA fragments. The two groups were found to have opposite polarities. It is shown that the four major transcripts can be aligned with, and may be functionally related to, SV40 and polyoma virus "late" mRNAs. It is also inferred that the 1.8- and 1.95-kb RNA species may be functionally related to the "early" transcripts of these papovaviruses.