A total of 63 primiparous hybrid sows were used in two experiments to study the effect of different fat and α-tocopherol levels in the lactation diet on the performance and milk production of sows and on the performance of sucking piglets. In experiment 1, the major differences in energy sources in the lactation diets were tapioca starch or animal fat. Fifteen sows received the low-fat diet (starch and fat content: 396 and 43 g/kg dry matter (DM)) and 16 sows were given the moderate-fat diet (starch and fat content: 286 and 75 g/kg DM) during 4 weeks of lactation. In experiment 2,16 sows were given a low-fat diet (diet 1: starch and fat content: 418 and 37 g/kg DM) and 16 were given a high-fat diet (diet 2: starch and fat content: 266 and 125 g/kg DM) during 4 weeks of lactation. In diet 2, 68 g animal fat replaced the 200 g starch present in diet 1. The mean α-tocopherol contents of foods in experiment 1 were 14 and 126 mg/kg diet and in experiment 2, 22 and 151 mg/kg diet. The live weight, backfat thickness and milk production of sows were not significantly affected by the different dietary fat levels (P > 0·05). The high dietary fat level increased the DM, fat and energy content of milk and the daily gain of piglets in the second part of lactation in experiment 2 (P < 0·05). The correlation between piglet growth and milk fat and milk energy intake (r) in experiment 1 were: 0·57 and 0·66 and in experiment 2 were 0·41 and 0·40 respectively. The utilization of whole milk and DM, fat, protein and energy content of milk for piglet growth was not influenced by dietary fat level. Varying the level of dietary α-tocopherol did not affect the variables investigated.