Two hundred and ten pigs were reared in three groups (according to genotype) under enriched conditions of large open-front sawdust-bedded barns. Eight hundred and twenty pigs were reared under standard conditions of small 15-animal pens in a conventional barn with partially slatted floors and natural ventilation. Production parameters including percentage mortality, feed conversion rate and average daily weight gain were calculated at the end of the fattening period. Stomachs, limbs and lungs were examined at slaughter in order to compare the number and severity of lesions between the enriched environment groups and the standard environment group. There was a significantly greater number of esophagogastric lesions in the standard environment group than in the enriched environment groups. No esophagogastric ulcers were observed in any pigs from the enriched groups, while 17.5% of stomachs from pigs in the standard environment group displayed this condition. There were no significant differences in the number of lung lesions associated with enzootic pneumonia between pigs from the standard and enriched environment groups. The limbs of animals reared in the standard environment had more lesions, especially in floor-contact areas, than those reared in the enriched environment (23.84% versus 1.08%). The production parameters measured were improved in the pigs from the enriched environment. These results suggest that the welfare of fattening pigs may be improved by the provision of enrichment in their housing environment. Evaluation of esophagogastric ulceration could be a useful indicator of welfare in pigs.