Experiments were designed to assess the relative importance of rates of cell division and cell enlargement in determining the final sizes of sorghum [Sorghum bicolor (L.) Moench, cv. ‘Oro’] leaves grown under varying degrees of water stress. Well‐watered sorghum plants were grown under atmospheric conditions which simulated natural daily cycles of air temperature and dewpoint in warm, moist conditions (experiment 1) and hot, dry conditions (experiment 2). In experiment 3, the plants were subjected to hot, dry conditions and five cycles of soil water deficit. Both the rate of increase of leaf area and the final leaf area declined progressively from experiment 1 to experiment 3. Between experiments 1 and 2, the average area per epidermal cell in leaf 11 decreased by about half as much as the leaf area. The area per cell did not decrease at all between experiments 2 and 3, despite a large decrease in leaf area. There was a progressive decline in the number of epidermal cells per leaf from experiment 1 to experiment 3. The proportion of stomatal cells changed only slightly. It was evident that the rate of cell division was at least as important as the rate of cell expansion in determining the final leaf area (assuming that epidermal cells are reasonably representative of all the cells in a leaf).