The purposes of this study were to establish piglet preweaning mortality rates on representative Ontario pig farms and to examine possible relationships between preweaning mortality and various management and environmental factors. Thirty randomly sampled farrow-to-finish herds were surveyed over a two year period. Mean preweaning mortality in liveborn pigs of 18.5+/-5.8 and 18.7+/-5.4 was recorded in the first and second years of the survey, respectively. Preweaning mortality was correlated positively with still-birth rate (r(1)=0.31, p(1)<0.1 (Year 1), and (r(2)=0.37, p(2)<0.05 (Year 2)) and with weaner pig mortality in the second year (r(2)=0.37, p(2)<0.05). Preweaning mortality was negatively correlated with herd size (r(1)=-0.30, p(1)<0.1 and (r(2)=-0.31, p(2)<0.1), crate utilization (r(1)=-0.52, p(1)<0.01 and (r(2)=-0.53, p(2)<0.01), and positively correlated with the number of farrowing crates per room (r(1) and r(2)=0.52, p<0.05).There was no relationship observed between preweaning mortality and housing and management characteristics such as the use of bedding or no bedding, batch farrowing versus continuous farrowing and single-use compared to multi-use farrowing rooms.It was felt that stockmanship was an important modifier of environmental effects.