Technical Abstract: Study of ingestion of Ponderosa pine (Pinus ponderosa) needles (PN) and other toxic plant materials by free-ranging ruminants is limited by a lack of rapid, inexpensive methods to estimate individual intake of the materials. We tested the potential for using near infrared reflectance spectroscopy (NIRS) of fecal samples as a means of estimating PN intake of cattle. Mature cows were divided into three groups (n=10/group) and fed a diet equal to 2% of their BW (DM basis) once daily. For each group, dried and ground PN were added to their diets at 0, 2, 4, 8, and 16% (DM basis) of the total diet (two cows/level of PN). Each group was fed a different basal diet, which was either ground alfalfa (Medicago sativa) hay, ground grass (mixed cool-season species) hay, or corn (Zea mays) silage. After 7 days of feeding these diets, fecal samples were collected on days 8 and 9. Dried and ground fecal material was scanned by a monochromator that collected spectra from 400 to 2500 nm at 2 nm intervals. This information was used to develop calibration equations and evaluate their performance. When spectra from fecal samples of all cattle were combined, the best composite set of wavelengths produced a prediction equation with an R**2 of .86 and a SE of calibration (SEC) of 2.9. When separate calibration equations were developed from feces of cattle on each basal diet, R**2 and SEC for the equations for alfalfa hay, corn silage, and grass hay were .89, 1.93; .95, 1.29; and .99, .61, respectively. Evaluation of fecal samples with NIR technology has good potential as a fast, inexpensive, and accurate method for estimating the amount of PN ingested by cattle.