Abstract: The soybean (Glycine max L. [Merrill]) var Itachi has 0.2 to 0.3% the urease activity found in developing embryos of a normal line, Prize. The hydroxyurea sensitivity and pH preference of this basal seed urease indicate that it represents a unique enzyme rather than an unusually low level of the normal seed urease. Itachi's seed urease is less sensitive to hydroxyurea inhibition (65-80% inhibition) than Prize seed urease (85-95% inhibition) and is more active at pH 6.1 and 8.8 than at 7.4, whereas the normal seed urease is least active at pH 8.8. Both properties of the basal seed urease are in agreement with the behavior of the leaf urease in extracts of Prize and Itachi leaves.