The Nilotic cattle of South Sudan support the socio-economic livelihoods of many rural and suburban communities, but their productive/reproductive characteristics are still poorly understood. This study investigated the growth performance of the Nilotic cattle under traditional husbandry system, by determining their live-body weight (BW), degree of maturity of weight (DM), absolute growth rate (AGR), relative growth rate (RGR), absolute maturing rate (AMR), and Kleiber ratio (KR), and how these traits change during postnatal development. The experimental procedure involved the measurement of heart girth (HG) and body length (BL) of 125 male and 136 female calves from birth up to the age of 16 months. Subsequently, the BW, DM, AGR, RGR, AMR, and KR of each calf were calculated. The results showed that on average, male calves weighed 4.68 kg, 7.98 kg, 2.23 kg, 10.23 kg, 2.21 kg, 2.24 kg, 3.97 kg, 10.38 kg, and 15.79 kg heavier (p<0.05) than females at birth, 2, 4, 6, 8, 10, 12, 14 and 16 months of age, respectively; and had the highest AGR (♂; 0.163 kg/day vs ♀; 0.139 kg/day) and KR (♂; 0.674 vs ♀; 0.591), while female calves had the highest (p<0.05) RGR (♀; 0.070%/day vs ♂; 0.065%/day), AMR (♀; 0.095% vs ♂; 0.056%), and DM (♀; 0.111~0.567 vs ♂; 0.072~0.340). Nevertheless, in both sexes, AGR, RGR, AMR, and KR values were higher (p<0.05) during the pre-weaning period than during the post-weaning period, though their respective declining rate was greater (p<0.05) in females (69.11%, 83.41%, 72.78%, and 75.09%) than in males (14.08%, 54.01%, 39.87%, and 41.94%). These results provide the first evidence for a fast growing and maturing pattern during the pre-weaning period in Nilotic cattle.