The aim of this study was to explore the effect of providing rubber mats in farrowing crates on the impact of lameness on sow welfare and performance. The study was conducted at Southern Research and Outreach Center, Waseca and involved 70 lame and 70 non-lame sows. An equal number of lame and non-lame sows were randomly allocated to farrowing crates with bare cast iron floors or to identical crates provided with rubber mats of 3 cm thickness placed over those floors. The frequency of getting up and dog sitting was affected by lameness on day 9 post-farrowing (P= 0.029) but was not affected on days 3 or 15 post-farrowing (P>0.05). The frequency of drinking water was affected by lameness on days 3 and 9 post-farrowing (P<0.05) but not on day 15 (P>0.05). Lameness did not affect the frequency of eating on days 3, 9 or 15 post-farrowing (P>0.05). The presence of rubber mats did not affect the frequency of getting up and eating of the sows (P>0.05), but it did affect the frequency of dog sitting and drinking water on day 9 post-farrowing (P=0.02). There was no significant difference in farrowing performance, body condition, LFI, total feed intake, feed intake on week -1 and week-2 post-farrowing between the groups. Back fat measurement at 109 d of gestation (odds ratio 0.832; 95% CI: 0.741-0.933) was negatively associated with the likelihood of having shoulder ulcers at weaning. The likelihood of shoulder ulcers was 3.0 (95% CI: 1.410-6.346) times higher on cast iron when compared to rubber mats on hind limbs (P<0.05). Parity, housing system and lameness were not associated with shoulder ulcers in this study. The survival of sows at 200 days post-weaning did not differ among groups (P>0.05). In general, the results indicate adverse effects of lameness on postural behavior and feed and water consumption during lactation.