Fecal indices. particularly fecal nitrogen concentration, have shown potential as indicators of diet quality of grazing cattle. Our study evaluated the utility of fecal nitrogen concentration and several other fecal chemical characteristics as indicators of protein status of cattle grazing southcentral New Mexico rangelands. Five esophageal fistulated steers and six steers equipped with fecal collection bags were used to evaluate diet quality. forage intake and fecal chemical composition for six collections during a 12-month period in 1984. Fecal phosphorus concentration was highly correlated with diet crude protein concentration (r²=.86). Fecal phosphorus appears to have potential for management decisions concerning protein supplementation. However. because of the lack of other research, we advocate further study before it is applied as a management tool to other ranges. Fecal nitrogen concentration was also correlated with diet crude protein concentration (r²=.67). Fecal phosphorus concentrations below 0.20%, and fecal nitrogen concentrations below 1.20% organic matter basis would indicate diet crude protein concentrations below those required for maintenance (7.7%, organic matter basis) on the range studied. Soluble phenolics and tannins associated with some forbs and shrubs can elevate fecal nitrogen concentrations relative to those in the diet. Based on insoluble fecal nitrogen concentrations. this was not a problem during periods of high (more than 50% of the diet) forb and shrub consumption in our study.