Two experiments were conducted to compare apparent ileal digestibilities and growth performance in pigs fed ground and extruded maize and sorghum. In Experiment 1, for digestibility, 24 early-weaned pigs (14 d old and 3.2 kg BW; EW) were given a terminal ileum exteriorization, and another 24 conventionally-weaned (CW) piglets (21 d old and 6.3 kg BW ) were fitted with simple T-cannulae. A n additional 8 piglets were employed for correction of endogenous amino acid excretions. Dietary treatments consisted of six differently processed maize and sorghum diets: 1. maize 900 µm, 2. maize 400 µm , 3. extruded maize, 4. sorghum 900 µm, 5. sorghum 400 µm, and 6. extruded sorghum. In Experiment 2, 150 piglets (21 d of age and 6.4 kg BW) were allotted to the same dietary treatments and used in a 33-d feeding trial. Reduced particle sizes of the grains from 900 to 400 µm tended to improve the apparent ileal digestibilities (AID) of Thr, Val, Leu, and Lys in maize and Thr, Val, and Leu in sorghum for EW, but not for C W piglets. The AID of essential amino acids were higher (P<0.05) in CW than in EW piglets. In true ileal digestibilities (TID) of essential amino acids in tested grains, there was a similar trend with the AID of essential amino acids, with the exception of improvement by 10.7% in EW, and by 8.1 % in CW piglets. In this study, however, the ileal digestibility of amino acids was highly (P<0.05 ) different between weaning ages. The differences were 19.6% in averaged AID , and 17.0% in TID of essential amino acids, respectively, between weaning ages. Extrusion of maize and sorghum did not improve the ileal digestibilities of amino acids, but the digestibility of Met in sorghum was improved (P<0.05) in EW pigs as compared with ground maize and sorghum. Between maize and sorghum, the ileal digestibility of amino acids was similar. During the overall period (d 0 to 33), diets with extruded maize and sorghum reduced ADFI (P<0.05) and improved gain/feed (P<0.05) by 3%o compared with diets with the ground grains. In conclusion, the ileal digestibility of amino acids in the grains was considerably affected by weaning ages of piglets, while ileal digestibility of amino acids and growth of pigs was not affected by reductions in particle sizes of maize and sorghum from 900 to 400 mm in complex weaner diets.