A 3-yr study was conducted to evaluate the effects of biotin on sow longevity, reproductive performance and piglet performance to weaning utilizing 161 sows and 414 litters. Sows and gilts were fed a basal corn-soybean meal diet (without any antibiotic or chemotherapeutic compounds) during gestation and lactation containing either 0 or .55 ppm added biotin. The basal diet contained .17 ppm total dietary biotin based on microbiological assay. Results indicated sow culling rates and weight gains, number of live pigs at birth, pig weights at birth and weaning, and the interval from weaning to rebreeding were similar for both treatment groups. However, sows fed the diet with added biotin weaned more (P less than .05) pigs/litter overall and at gestation-lactation period 1 than did sows fed the basal diet without added biotin, although biotin did not increase (P greater than .10) the number of pigs weaned at gestation-lactation periods 2 through 5. The incidence of dermatitis, hair loss and soundness of feet and legs did not appear to be affected by adding biotin to the diet. Thus, the addition of .55 ppm biotin to a corn-soybean meal diet fed during gestation and lactation did not improve any of the criteria measured except number of pigs weaned overall.