New series of 6-(arylthio)uracils, 6-(4-substituted-1-piperazinyl)uracils, 2,4,5-trioxo-1H,3H-benzothiopyrano[2,3-d]pyrimidine and 5-aryl-2,4-dioxo-1H,3H-pyrimido[5,4-f]benzo[1,4]thiazepines have been prepared and screened for their in vitro activity against herpes simplex-1 virus (HSV-1) and human immunodeficiency virus-1 (HIV-1). The in vitro cytotoxic activity was also evaluated. The results of biological testing revealed that compound 5b showed marginal activity against HSV-1, while compounds 5b and 5f exhibited marginal activity against HIV-1. The rest of the tested compounds were found devoid of antiviral activity against both HSV-1 and HIV-1.