Background and Objectives: The molecular genetic of the human herpes virus 8 (HHV8) has now been characterized the pathogenesis of kaposi sarcoma (KS). This study attempted to determine the rate of HHU-8 infection in KS in an Iraniann cross sectional study. Method & material: In this cross-sectional study, we used paraffin-embedded specimens of 54 clinically well-characterized kaposi sarcoma cases. Routine streptavidin- biotin- peroxidase immunostaining with diaminobenzidine was performed on paraffin-embedded tissue of 54 KS cases using a monoclonal antibody directed against the c-terminum of the latent nuclear antigen-1 molecule of HHV-8 (colone 13B10; Novocastra) at 1:50 dilution. Result: Positive HHV8 nuclear staining was detected in the nuclei of the spindle cells and endothelial cells of the vascular channels in about 88.9%. (48/54) of all cases and in 90.56% (48/53) of cases with presence of residual tumor in specimen (1 of 54 paraffin blockes has no residual tumor). HHV8 was detected in higher percentage in plaque and nodule stage rather than patch stage with p=0.035. HHV 2 was detected in lesser percentage in lesion of hand and trunk rather than other sites with p=0.042. There was no significant difference in HHV8 positivity between the presence of HHV8 and age, gender and history of immunosuppression. Conclusion: Immunohistochemical detection of LANA HHV-8 is helpful in diagnosis of suspicious cases of KS, specially in lesion of plaque and nodule stage that are not located only in hand or trunk.