The purpose of thIs investigation was to determine whether correlation exists between the O-R potential and the biochemical oxygen demand of settled sewage. The source of the samples was the effluent end of the primary clarifier at the V.P.I. Sewage Disposal Plant. The investigation consisted essentially of performing the standard biochemical oxygen demand determination and the oxidation-reduction potential determination on similar sewage samples. The data obtained were statistically analyzed and graphically presented. The standard deviation was ascertained and a ninety percent confidence limit was established. The final results based on statistical methods of analysis show that no valid correlation exists between O-R potential and B.O.D. of settled sewage. / Master of Science