Performance of finishing pigs in hoop or confinement during summer and winter was evaluated in Iowa. Hoops are large tent-like shelters with corn-stalks or straw for bedding. During summer and winter seasons for thre years, 1998-2001, six trials were conducted using three hoops strcutures or mechanicallly ventilated confinement barn with slatted floors. A total of 3,518 pigs started the trials. Summer trials were June to October and winter trials were Novemeber to April. Target stocking density was 1.1 sqyare meters for hoop strcuture, and 0.74 square meters for confinement buildings. Identical corn-based diets were fed adlibitum from 16-118 kg for 127 days. Pigs were scanned before harvest for backfat and loin muscle area. When seasons were merged hoop-fed pigs had more backfat, smaller loin muscle area, less lean percentage, than confinment housed pigs. When season x housing type interactions were observed, summer hoop-fed pigs had greater ADG, required fewer days to market had similar ADFI and gain:feed compared with confinement fed pigs. Lean gain/day and efficiency of lean gain did not differ between housing systems. During winter hoop fed pigs had similar ADG required more days to market, had greater ADFI, less gain to feed, lees lean gain/day than confinment-fed pigs. Percentage of culls and mortalities did not differ between housing system. During summer there was a trend for fewer ligh weight pigs at marketing from hoops than confinement. Bedding use in hoops was 92 and 122 kg/pig for summer and winter respectively. Performance of finishing pigs in bedded hoop structures depends in part on thermal environment.