In this study, it was aimed to model the diameter distribution of Scots pine (Pinus sylvestris L.) stands inKastamonu region. The effects of various stand characteristics (number of trees, mean diameter, stand density, siteclass, crown closure, developing stage and stand type) on the determination of the most appropriate distributionfunction were also investigated. 890 sample plots data obtained from the General Directorate of Forestry archivewere utilized as study material, and Beta, Gamma (with 2 and 3 parameters), Johnson SB, Log-normal (with 2 and3 parameters), Normal and Weibull (with 2 and 3 parameters) probability density functions were used to model thediameter distributions. Kolmogorov-Smirnov (KS), Anderson-Darling (AD), Chi-square (X2 ) and Error Index (e)criteria were used to determine the success of probability density functions and to decide the most appropriateones. The effects of stand characteristics on the decision of the most suitable function were also determined byKruskal-Wallis and Chi-square tests. As a result of comparisons, Johnson SB was determined as the mostsuccessful probability density function. While the success of the probability density functions was affected by thenumber of trees, mean diameter, crown closure, developing stage and stand type, it was not affected by standdensity and site class.