Flood is one of the oldest forms of natural hazard in the world and the magnitude-recurrence interval relationship is very important to a designer or planner of hydrological projects. in designing and planning of hydraulic and water resouces projects continuos hydrological data of river flow is necessary such that the flow pattern or trend can be ascertained and hence the design can be made accordingly. this thesis is envisaged as an investigatin of the effect of length of recors on the flood magnitude-return period relationship for different statistical distributions, viz, the Gumbel Extreme Value Type 1, Type II, Pearson Type III, Log Pearson Type III, and the curve fitting technique (Graphical Method). Also the merits of each distribution as appleid to this catchment area is examined, being the River Kelantan at Guillermerd Bridge recording station. A brief historical account of statistical wroks carried out by prominent reserarches is given and the relevant probability and statistical theories are discussed, in relation to application of hydrological data analyis. The actual extreme-flow records of the river is extracted. The choice of this river is purely due to the relatively long duration of continuous flow records available.