In the present investigation Catharanthus roseus, an important herb used in traditional as well as modern medicine, exposed to water deficit stress and possible changes in chlorophyll contents, photosynthesis rate, transpiration rate, growth parameters as well as total alkaloid content and vincristine and vinblastine levels were studied. Seedlings subjected to 4 different water-regimes. Experimental samples irrigated once every week or every second and third week and the control irrigated every day. Drought had adverse effect on height, weight and Relative water content of periwinkle. The photosynthetic activity and transpiration rate significantly decreased with increasing drought level. Total protein decreased to 77% and total chlorophyll decreased by 27%. Total alkaloid content significantly increased to maximum 187% compared to the control. Vincristine and vinblastine content of the seedlings grown under treatments3 increased to 175% and 171% compared to the control, respectively
