Physiological effects of drought were studied in two pea (Pisum sativum L.) cultivars to determine their relative ability to withstand this stress. Drought stress decreased dry weight and relative turgidity, reducing sugar, sucrose and starch concentrations, ribulose‐l,5‐ diphosphate carboxylase (E.CA.l.l.39) activity, and net photosynthesis in both drought‐susceptible ‘Alaska’ and drought‐resistant ‘Hardy’ peas. Decreases in dry weight, carbohydrate concentration, enzyme activity, and net photosynthesis were greater in the drought.susceptible cultlvar, but respiration rate, determined by infrared analysis, was decreased more in the tolerant cultivar. SADH (succinic acid‐2,2‐dimethylhydrazide) treatment increased relative turgidity and ribulose‐l,5‐diphosphate carboxylase activity under drought stress, but decreased respiration and rate of water uptake in both cultivars under nonstress conditions. Sucrose concentration increased in Alaska peas whereas net photosynthesis decreased in Hardy peas after SADH treatment. SADH had no effect on reducing sugar and starch concentrations. It was concluded that SADH treatment probably enabled plants to tolerate stress longer by decreasing energy requirements and metabolic degradation rates.