Persistent investigations for the identification of novel anti-herpetic drugs are being conducted worldwide, as current treatment options are sometimes insufficient. The immunomodulator, ammonium trichloro[1,2‑ethanediolato‑O,O']‑tellurate (AS101), a non‑toxic tellurium (Ⅳ) compound, has been shown to exhibit anti‑viral activity against a variety of viruses in cell cultures and in animal models. In the present study, the anti‑viral activity of AS101 against herpes simplex virus (HSV)‑1 and 2 was investigated in vitro. The results demonstrated that AS101 significantly restricted HSV‑2-induced plaque formation and reduced the infectivity of the HSV‑2 yield, while HSV‑1 was affected to a lesser extent. The incubation of mature HSV‑1 and HSV‑2 viruses with AS101 had no effect on viral infectivity, indicating that the compound interrupts de novo viral synthesis. The addition of AS101 at up to 9 h post‑infection had almost the same effect as did the addition of the drug together with the virus (it maintained 80% of its total anti‑viral capacity). Quantitative PCR and immunofluoresence staining of viral structural proteins revealed that the viral DNA and protein synthesis stages were not interrupted by the administration of AS101. By contrast, in the presence of the compound, significantly fewer viable viruses (≥2 log reduction) were recovered from the AS10‑treated cell cultures. Of note, when we determined the viability of the intracellular virus, formed in the presence of the compound, a less severe (≤1 log) effect was observed. Taken together, these data strongly suggest that AS101 primarily interferes with late stages of viral replication, such as viral particle envelopment or egress, leading to the production of a defective virus progeny.