The study was carried out with the aim to determine the effects of seed size and shape on field performance of maize. In the study, three different kernel sizes/shapes 4.5-5.5 mm (SF and SR), 5.5-6.5 mm (MF and MR) and 6.5= mm (LF and LR) were used. Grain yield and ear characteristics (ear diameter, ear length, the number of kernels per ear, ear weight, 1000-kernel weight and hectoliter weight) were significantly affected by seed size. Effect of seed shape on examined characteristics was non-significant. Effect on grain yield and ear charasteristics of large seeds were higher compared to medium and small seeds. The results showed that the grain yield (the highest grain yield 12.29 and 11.71 t/ha was determined from LR seeds in both the years) was higher in seeds with large size/shape in corn. The maximum ear diameter (39.0 and 40.7 mm, respectively) and ear length (22.3 and 22.7 cm, respectively) were obtained from LR seeds in both the years. The highest number of kernels per ear was determined from LF (664.7 grain) in first year and LR seeds (672.3 grain) in second year. The highest ear weight was obtained from LF seeds (254.0 and 249.0 g, respectively) in both the years. The highest 1000-grain weight was determined in LR (329.3 g) in first year and LF seeds (330.0 g) in second year. The maximum hectoliter weight was obtained from LF (79.7 kg) in first year and LR seeds (78.3 kg) in second year.