The objective of this study was to determine the effect of oats in diets on the performance of finishing pigs in deepbedded hoop barns. Oats may be used in limited quantities in swine diets. High-quality oats are typically valued at 80 to 85% the feed value of corn when fed to finishing pigs. Finishing barrows (240 head) were used to evaluate the dietary effects of oat-based diets in hoop barns. Six pens of 10 barrows each were fed three diets for four replications for two seasons, winter and summer. The summer season consisted of May through September. The winter season consisted of November through March. Two years were used to minimize seasonal variation. The oats used in the study had a test weight of no less than 36 pounds per bushel. The diets were isolysinic, on a calculated analysis. Pigs fed both the 20 and 40% oat diet performed similarly to those fed a control corn–soybean meal diet. Addition of oats up to 40% of the diet for finishing barrows greater than 150 pounds to market weight (270 pounds) in deep-bedded hoop barns, had no effect on average daily gain, average daily feed intake, feed efficiency, backfat, loin eye area, or lean percentage. There may be several factors that led to these results. The use of barrows, the use of heavy finishing pigs, the type of environment, and the heavy test weight of the oats used in the study may be possible explanations for the results. The performance of the pigs fed the 40% oat-based diets, was difficult to explain. More research may be needed. Based on these results, heavy test weight oats are a viable and useful feedstuff for pigs fed in deep-bedded hoop barns and can be used up to 40% of the diet for barrows over 150 pounds to market. Oats can be substituted for corn and some soybean meal in pig diets. The use of oats in pig diets in hoop barns should be based on economical consideration and not on anticipated changes in pig performance or carcass traits.