Abstract: The objective of this study was to observe water stress tolerance in cotton seeds, when mepiquat chloride is used as seed treatment. Increasing drought resistance of cotton seedlings by accelerating root growth is an important practical implication. The study was conducted on effects of mepiquat chloride (1, 1-dimetheyl peperidinum chloride) on drought resistance of cotton seedling. The cotton seeds were soaked for night in mepequat chloride solution i.e. 0, 500, 1000, 1500 and 2000 ml L- 1. Water stress was given after thirty days after sowing, for nine days and data were collected for root length, shoot length, fresh weight and dry weight. Firstly, mepiquat chloride seed treated plants were well irrigated and subjected to severe stress. It indicated that petiol length and shoot length decreased, while root length, fresh weight and dry weight increased with high concentration of mepiquat chloride. Cotton seeds treated with high dose of mepiquat chloride may elongate the days taken to emerge first true leaves. With the withdrawal irrigation, mepiquat chloride treated seedlings at all concentration maintained higher root growth, shorter stem length more fresh and dry weight than non-treated seedlings.