Root systems of sorghum plants grown in soil were measured at 9, 14, and 17 days from sowing. Data for 10 parameters of the root systems are reported. Notable features of the results were the low average diameter of the root members (c. O' 2 mm) and the very high mean extension rate (c. 0�8 cm per member per day), which was five to eight times higher than values reported for barley.