Pre-weaning mortality (11.9% as estimated by M.L.C., 2000) continues to be a major economic and welfare problem in commercial indoor pig production. The main causes of mortality are crushing by the sow and low viability/starvation. Both of these causes of death may be as a result of increasing sow body size and smaller piglet body size as a result of intense genetic selection for increasing litter size. However it is unclear whether sows are consistent across parities in their level of pre-weaning mortality. Therefore this study aimed to examine individual differences in piglet mortality of sows throughout their reproductive life, investigate factors likely to affect piglet mortality, and to assess whether piglet mortality may be a candidate trait for genetic selection.