The objective of the study was to evaluate the impact of housing systems on the health and welfare of grower and finisher pigs. Forty-seven "animal friendly" farms meeting Swiss criteria and participating in a Swiss subsidy program and 37 farms using traditional housing with slatted floors were evaluated in an epidemiological field study. Group-health evaluations and individual clinical examinations were performed during four visits to each farm. Evaluation of pig behaviours associated with health and welfare were assessed through indicators including presence of lesions on the snout, ears, shoulders, legs and tail. General group-health evaluations included lameness, respiratory disease, diarrhoea, ear biting, skin abnormalities, injuries, abscesses, sunburn, recumbency, ill-thrift and behavioural abnormalities such as dog sitting and tail biting. Data on management practices, medical treatment, mortality and results of slaughter inspections were also collected, and the type of housing described. Pooled faecal samples were collected and examined for intestinal parasites. Statistical analyses included descriptive statistics of indicators of health and welfare and logistic-regression analysis accounting for group effect using generalised estimation equation (GEE). Findings indicated a high health status of pigs in Swiss finishing farms. Data from the individual clinical examination were more sensitive compared to the group-health evaluations. Both the individual clinical examination and group-health evaluation indicated that "animal friendly" housing had positive effects on health and welfare of fattening pigs.