The importance of modeling stand structure in forestry cannot be over emphasized as it has become imperative for forest managers to quantify and predict the growth and yield of the forest estate. However this requires distribution models that are useful in predicting growth and yield over the years. Therefore this study modelled the diameter distribution of Nuclea diderrichii in Forestry Research Institute of Nigeria. Data were collected from four different years (2011, 2012 and 2013). Two distribution functions which include 2p weibull and Gamma distribution function were fitted to the data set. More so, two fitting methods which include maximum likelihood and method of moment were adopted for fitting the weibull and gamma distribution. The criteria for assessing the best fitting procedure were based on Kolmogorov-Smirnov, Cramer-von Mises, and Anderson-Darling test. The Kolmogorov-Smirnov, Anderson darling value of the weibull was 〖2.2e〗^(-16) and 〖2.927e〗^(-06). While the Kolmogorov-Smirnov, Anderson darling value of the gamma distribution was 〖2.2e〗^(-16) and 〖2.930e〗^(-06) respectively. Therefore, method of moment was judged to be the best fitting procedure for estimating both the weibull and gamma distribution in the study area. The application of the weibull and Gompertz model provided information on average height and volume per hectare. The information provided in this study is useful for management decisions such as prescribing silvicultural treatment to the Nuclea diderrichii plantation.