Abstract: Pesticides are extensively used all over the globe for the control of pest population responsible for reduction in yield and among them fungicides are the specifically used to control fungal plant pathogens. An In-vitro plant study was conducted to assess the effect of Mancozeb on early growth parameters on two Mustard (Brassica juncea) varieties i.e. RH- 30 and Laxmi. Mancozeb (75% WP) is a widely applied contact fungicide for control of various diseases but several toxicity issues are associated with Mancozeb. Mustard is one of the most important oil yielding crops and is majorly used for various purposes such as medicinal uses, condiment and industrial uses. In the experiment three different doses of Mancozeb (75% WP) i.e. 1 mg.kg-1 Half Recommended Dose (½RD), 2 mg.kg-1 Recommended Dose (RD) and 4 mg.kg-1 Double Recommended Dose (2RD) applied on RH-30 and Laxmi varieties. Results revealed that, RD and 2RD reduced the germination up to 30–60 % in variety RH-30 whereas in variety Laxmi reduced germination percentage is 17–55 % in comparison of control. The overall length of plants of variety Laxmi was found to be increased in comparison of control but in plants of variety RH-30 the results was just opposite. Overall results indicate that excess amount of Mancozeb induced stress in both mustard varieties which resulted in low germination percentage. Whereas after seven days, Laxmi resulted in better growth than RH-30 plants. Also, Seeding vigour was recorded higher in Laxmi than RH-30.