The sequence analysis of the genomic region of Marek's disease virus (MDV) serotype 2 (MDV2) which had homology with the gene encoding MDV serotype 1 (MDV1) homologue of glycoprotein C (gC) of herpes simplex virus revealed that there was a single open reading frame (ORF) capable of encoding 479 amino acids. The predicted protein from this ORF had strong hydrophobic regions in both the amino and carboxyl termini and several potential N-linked glycosylation sites, as seen in those from the ORFs of MDV1 and MDV serotype 3 (MDV3 = herpesvirus of turkeys (HVT)) gC homologues. By northern-blot analysis using a DNA fragment located in the MDV2 gC homologue ORF as a probe, 3.6 and 1.9 kb RNA transcripts were identified in MDV2-infected cells. When the alignment of amino acid sequences of the gC homologous genes of three MDV serotypes were compared, the homology between MDV1 and MDV2 and that between MDV1 and HVT showed about 76% identity, whereas that between MDV2 and HVT was about 70% identity. These results suggested a possibility that the evolutionary distance between MDV1 and MDV2 and between MDV1 and HVT is shorter than that between MDV2 and HVT.