Sandpaper oak is a com¬mon woody plant in many parts of the Southwest. Cattle and deer use sandpaper oak as part of their diet in late spring to early summer when other forage is limited. Mowing may be one method to alter the palatability and/or nutritional value of this plant species. We examined effect of spring and fall mowing on the nutritional quality and secondary chemistry content of sandpaper oak. Both protein and lignin were positively affected by mowing treatments. Crude protein of young leaves was typically higher in mowed treatments than in unmowed areas, but was not different for spring and fall mowing treatments. Lignin content of both young and mature leaves was lowest for the fall mowing treatment. Condensed tannins increased with leaf maturity, while total phenolics were greater in young leaves. Condensed tannin content of leaves in the two mowing treatments did not differ. Total phenolics were lower in leaves from the growing season mowing treatment than from the dormancy mowing (second year only). Crude protein content of both young and mature leaves of mowed oak was higher in fall than surrounding grasses collected at the same time. New growth from mowed sandpaper oak could be a protein source for cattle and wildlife during certain times of year. Tannins and phenolics can decrease palatability, impair digestibility and rumen protein dynamics, and can be toxic at high intake levels. Toxicity should be less problematic when rangelands are lightly to moderately grazed and contain adequate plant diversity.