Peste des petits ruminants (PPR) is an important viral disease of sheep, goat and other small ruminants, imparting substantial economic losses. In current study, antiviral activity of six dilutions of Nigella sativa (N. sativa)alcoholic extracts against the PPRV was investigated in vitro. Vero cell lines infected with PPRV were treated with six dilutions alcoholic extracts of N. sativa (200, 100, 50, 25, 12.5 and 6.25 µg/mL). The antiviral effects were judged by 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide colorimetric (MTT) assay. Plaque reduction assay was used to test the mode of action. Out of six dilutions, three dilutions (50, 25, 12.5 µg/ml) showed significant antiviral activity and cell survival was more than 50%. Two dilutions of N. sativa (200 µg/ml and 100 µg/ml) extracts showed cytotoxicity to Vero cell lines. In the plaque reduction assay, alcoholic extracts of N. sativa (50 µg/ml) significantly reduced the plaques count as compared with the control negative (P<0.05) in all the tested modes of action. The current experiment revealed that the alcoholic extracts of N. sativa (50 µg/ml) could increase the viability of infected cells, and curtail the cytopathic effects of PPRV. N. sativa seed extracts should be explored in field conditions for the control of PPR.