Background: Blackgram is one of the important pulse crops belongs to the Papilionaceae family. Seed germination and seedling growth are a very important step in the survival of a plant. Water stress is one of the important factors affects seedling growth. Methods: An experiment was conducted to study the effect of water stress on seedling growth in twenty-one blackgram Vigna mungo (L.) Hepper genotypes at the pot culture yard of Annamalai University during March 2018. The water stress was created by using Polyethylene Glycol (6000 MW) in different concentrations (0%, 10% and 20%). Different phenotypic characters were recorded such as shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight at two different levels of treatment and control. The experiment was laid in a completely randomized design with two replications. Result: The combined analysis of variance revealed significant differences (p less than 0.001) among genotypes, treatments and genotypes × treatments interaction. The highest stress tolerance index (STI) was recorded by the genotype ADT-5. Based on clustering and ranking, the genotypes ADT-5, KGB-28, RU-16-9, VBG-10010 and VBG-12062 were classified as drought-tolerant. Overall, pot culture screening of 21 blackgram genotypes for drought tolerance at seedling stage using various concentrations of PEG 6000 resulted in the identification of drought-tolerant genotypes, where ADT-5 showed the highest tolerance followed by KGB-28 and RU-16-9.