The objective of this study was to determine the effects of raising pigs in small versus large pens during the grow-finish period on health and number of lesions of the finisher pig. The experiment was conducted from April to July, 2009. One wean to finish site within a large Midwestern commercial production system was used. There were four rooms on this site. A total of 3,162 pigs were used to compare health status and frequency of lesions. Within each room, one side of the aisle was set-up with the small pen treatment (SP; n = 45 pens; [34 pigs/pen]), while the other side was set-up with the large pen treatment (LP; n= 6 pens; [272 pigs/pen]). Therefore, both treatments were represented in each room. All pigs were kept in smaller pen configurations for 4 weeks and then the back gates of eight consecutive pens in the LP treatment were opened. Pens were mixed sexed and when the first market group of pigs reached targeted market weight the trial was terminated. One day prior to trial termination, a total of 316 pigs (10% of the population) were visually assessed by two observers for the frequency of lesions. Lesions were defined per the PQA Plus definition of skin lesions (NPB, 2007), as “…breaks that completely penetrate the skin, such as bites or other lesions that penetrate through the skin.” Lesion scores were analyzed using the PROC GLIMMIX procedure of SAS. When a pig was identified within their home pen as requiring medication, the drug type, number of pigs treated, the dose amount and cost per dose were recorded and this information will be presented descriptively. There were differences in lesion frequency with pigs housed in large pens having a higher (P < 0.05) number of lesions compared to pigs in the small treatment. This was consistent across all locations on the pig. More pigs were treated in the large pen (n = 198) compared to the small pen (n = 158) and consequently a higher drug cost was noted for large pens ($127.63 vs. $95.47). Therefore in conclusion, larger pens had higher lesion frequency and higher drug treatment costs.