We have previously found the sequence having potential for encoding a new protein in the human leukocyte antigen (HLA) class II region. The predicted amino acid sequence showed a significant sequence homology to the Xenopus double-stranded RNA-binding protein (Xlrbp) and the human cellular protein bound to the transactivation response (TAR) of human immunodeficiency virus type-1 (HIV-1) RNA (TRBP). Reverse transcription-polymerase chain reaction (RT-PCR) with poly(A)(+) RNA prepared from human peripheral lymphocytes and direct sequencing analyses in this study showed that the transcripts of the gene encoding the putative RNA-binding protein occurred in human cells: the gene was provisionally named Homo sapiens RNA-binding protein (hsRBP). From the result of Southern blot analyses, it appears that multiple copies of hsRBP are present in the human genome. Together with the known cDNAs having a high sequence homology to hsRBP, the data presented here suggest that the multigene family of the double-stranded RNA-binding protein exists in the human genome.