Background: Herpes simplex virus (HSV) is prevalent in today’s world population, and there is evidence of potential HSV reactivation in patients with immune deficiency induced by acute stroke. However, the data on the use of antivirals in the setting of stroke are scarce. The aim of this study was to evaluate the reactivation of HSV-1 in patients with stroke, using several methods, and to assess the efficacy of acyclovir in the treatment of experimental stroke. In the employed methodology, PCR and dot-ELISA were used to detect the occurrence of HSV-1 in patients with acute stroke. White mice were infected with HSV-1 and experimental stroke was simulated. The infected mice with stroke were subdivided into two groups: one of them received no treatment, while the other one was treated with acyclovir. The level of HSV-1 reactivation was determined by the methods used in human patients. The brain tissue of experimental animals was also subjected to morphological and morphometrical study. The results of such work reveal that, by the applied serological method, HSV-1 was found in all patients with stroke. Herein, the increased level of HSV-1 was seen in the brain tissue and blood in 100% of the experimental infected animals. However, the use of acyclovir suppressed reproduction of HSV-1. Hence, it can be concluded that clinical and laboratory studies have demonstrated the different sensitivity of Dot-Elisa and PCR, with the former being more sensitive. Moreover, the use of acyclovir in the experiment inhibited viral reproduction and further development of viral infection. Still, chemic lesions in the brain persisted.