The antiviral activity of plants Silybum marianum (seeds), Chenopodium album (whole plant) and Nigella sativa (seeds) were evaluated against Peste des petitis ruminants virus (PPRV) and Foot and Mouth Disease virus (FMDV) in this study. Methanolic extraction of these plants was done by using Soxhlet apparatus and extracts were dried by using rotary evaporator. Six dilutions of each extracts 100, SO, 2S, 12.S, 6.2S, 3.12~g/ml were made in distilled water. Vero cells were infected by PPRV and BHK-21 by FMDV respectively. The herbal extracts assays of antiviral and cytotoxic were carried out in cell culture plates. Each well of 96 well cell culture plate were seeded with 104cell/ml of cell suspension. Cell counting was performed by hemocytometeric method. Positive and negative controls for antiviral and cytotoxic assay were also used, incubated the 96 well cell culture plates at 37°C for 4 days. After this incubation, MTT [3-(4,S-dimethylthiazol-2-yl)- 2,S-diphenyltetrazolium bromide] colorimetric assay were used for the determination of their quantification. Endpoint of this assay was considered in terms of cell survival percentage. Results were compared for qualitative variables using Chi-square technique and quantitative variables by linear regression analysis. 1 OO~g/ml and SOIlg/ml concentrations of Chenopodium album showed cell survival percentages of 87.9% and 86% respectively in PPRV and all six test dilutions of same plant showed no cytotoxicity for Vero cells. IOuug/ml and
SO~g/ml concentrations of Chenopodium album showed cell survival percentages of 88.5% and 87.2% respectively in FMDV and all six test dilutions of same plant showed no cytotoxicity for BHK-21 cells. Two concentrations of Nigella sativa 50!J. glml and 25!J. glml showed prominent cell s urvival of 85% and 84% respectively in PPRV and only one concentrations l Ouug/ml were found cytotoxic.Two concentrations of Nigella sativa 50uglml and 25!J.glml showed prominent cell survival of 79% and 77% respectively in FMDV and only one concentrations IOuug/ml were found cytotoxic. Only IOuug/ml of Silybum marianum has shown cytotoxicity and 50!J.glml and 25!J.glml shown prominent antiviral activity 91% and 85% respectively in PPRV. In FMDV l Otlug/ml of Silybum marianum has shown cytotoxicity and 50!J.glml and 25!J.g/ml shown prominent antiviral activity 93% and 91 % respectively. The results of present study are helpful in the treatment of Peste des petitis ruminants and Foot and Mouth Disease.