The present study was carried out to investigate the structure of thymus of rabbits and cellular immune response after vaccination with viral haemorhagic septicemia vaccine. The present work was carried out on fifteen apparently healthy rabbits which were divided into two groups, control non-vaccinated and vaccinated. The rabbits were humanlysacrificed, eviscerated and subsequently tissue specimens from the thymuswere takenfor histological and immunohistochemical studies of thymus. Serumsamples were collected for measurement of cytokines, interleukin 2 and 6 (IL-2 and IL-6) and tumer necrosis factor alpha (TNF α). Present results showed that the thymus was lobulated organ consisted of peripheral dark cortex and central light stained medulla. Cortex consisted of high population of small dark lymphocytes and number of epithelial reticular cells. Medulla consisted of large lymphocytes, epithelial reticular cells and Hassals corpuscles. The results showed that serum IL-2 and IL-6 concentrations were significantly increased in vaccinated rabbits, when compared to control non-vaccinated rabbits. On contrast, the results showed that there was non-significant increase in serum TNF-α concentration in vaccinated rabbits when compared to control non-vaccinated rabbits. There were positive immunostaining reactions to CD4 and CD8 markers in vaccinated rabbits when compared to non-vaccinated groups, also there were positive immunostaining reaction to CD20 and CD68 markers. The present results indicated that vaccination of rabbits with VHSV increase level of cellular immune response and level of cytokines produced by the thymus.