Differences in osmoregulation were found in the leaves of closely related breeding lines and cultivars of chickpea (Cicer arietinum L.). Osmoregulation was determined from measurements of osmotic potentials (using thermocouple psychrometers) and relative water contents made on the leaves of plants grown in the glasshouse, and stressed by withholding water in a controlled-environment chamber. The controlled-environment measurements of osmoregulation were associated with increases in grain-yields in field experiments conducted at various sites in northern New South Wales in 1987 and 1988. The yield increases ranged from approximately zero in low-water-deficit environments (site mean yield, 3.5 t ha-1) to approximately 20% in high-water-deficit environments (site mean yield 1.3 t ha-1). These results suggest that osmoregulation may be a useful selection criterion in breeding for greater yields in water-limited environments. © 1991.