Abstract: The present study aims at investigation of the response of Catharanthus roseus shoots to salinity (control, 100 and 150 mM) and drought (control, two-weeks-regime and three-weeks-regime) for a period of 4 months. Total proteins, amino acids, proline and vincristine alkaloid contents were estimated before and after stress. Both salinity and drought reduced the amount of shoot total proteins while increased the amount of total amino acids which has been attributed to enhanced protein degradation and/or de novo synthesis of amino acids. Accumulation of proline after both stresses supported the previously recorded correlation between cellular proline levels and the capacity to survive environmental stresses. Salinity and drought resulted in increased amounts of the amino acids serine, methionine and arginine, which are considered precursors for the synthesis of glycinebetaine, nicotinamide and putrescine that are commonly encountered osmolytes that accumulates in plants under salinity and drought stresses. Vincristine alkaloid content increased with two peaks at 150 mM salinity at the 2nd month of treatment and at the 4th month of the highest drought level. The increase in vincristine content was attributed to the raised levels of arginine subsequent to stress that could derive the biosynthesis of putrescine. This polyamine was found to induce nitric oxide biosynthesis which acts as chemical elicitor for indole alkaloid production of C. roseus shoots.