Quantifying the yield potential of maize at any given site is a key to understand the existing yield gaps and to identify the most important constraints in achieving optimal yield and profit. A well parameterized and validated APSIM model was used to assess the productivity and yield gap of maize cv Kanchan 101 from multi-year long-term and completed experiments. A total of 30 districts with 74 soil profiles of Madhya Pradesh were considered for the study. For the 30 selected sites, the rainfed potential yield of maize (Ywp) ranged from 3.3 to 5.2 t ha-1 whereas the districts mean yield (Yf) ranged from 0.7 to 3.1 t ha1 giving yield gaps ranging from 1.7 to 3.1 t ha-1. It was observed from the long-term simulation study that there is a good potential to improve the grain yield of maize crop by 3.0 t ha-1 provided optimum dates of sowing and good management practices are followed in the state.