Summary. -The HindIII-HincII fragment of the 5.5 kbp H11 HindIII clone of ovine herpesvirus 1 (OvHV-1) was cloned and its primary structure was determined by preparation of nested deletion subclones and their sequencing. Sequence analysis of the overlapping clones revealed that 3239 bp OvHV-1 fragment contains complete thymidine kinase (TK) gene, a partial open reading frame of ORF20 and that encoding glycoprotein H (gH). The conserved OvHV-1 TK displayed the highest similarity to homologous TK proteins encoded by members of the Macavirus genus of the Gammaherpesvirinae subfamily. These data including our previous analysis of the partial sequence of VP23 homologue might serve as further evidence that OvHV-1 should be categorized within the genus Macavirus of the Herpesviridae family.Keywords: ovine herpesvirus 1; thymidine kinase; Macavirus; Gammaherpesvirinae * Corresponding author. E-mail: viruzelo@savba.sk; phone: +421-2-59302463. Abbreviation: CPE = cytopathic effect; FUDR = 5΄-fluoro-2΄-deoxyuridine; HSV-1 = herpes simplex virus 1; JSRV = Jaagsiekte sheep retrovirus; MuHV-4 = murid herpesvirus 4; OvHV-1 = ovine herpesvirus 1; SPA = sheep pulmonary adenomatosis; TK = thymidine kinase