Frequency analysis has become generally accepted as a tool in hydrologic studies. However, it is generally accepted that no single technique of fitting frequency distribution of flood flows is expected to be applicable to all climatic conditions. An annual peak rainfall depth for 40 years record were extracted from record obtained from Ibadan Metrological station. Therefore, in the comparism of the performance of various probability distribution methods used to fit rainfall data with determination of flood characteristic of River Ogunpa, four flood probability distribution methods and statistical methods were used and evaluated in the analysis to determine the probability distribution that best fit the data.