FreqPlot is a frequency analysis program used to compute return period rainfall and flood peak discharge. It was developed by Darde deRoulhac of Payson, Arizona and revised and graphically enhanced by HAREC s.r.l. of Rome Italy. FreqPlot enables a comparison of the data and fitted curves on four probability distribution plots including Extreme Value, Log Extreme Value, Normal and Log Normal. This comparison permits the user to select the best fitting distribution curve to the data and represents a significant enhancement over the Bulletin 17B method.