This paper presents a correction to the dual dynamic programing algorithm, which was initially published by Pereira and Pinto <1985>. We show that as originally published, the algorithm is correct only for two-stage problems. For problems with three or more stages, there is a term that must be added to the original equations of Pereira and Pinto in order to meet the Benders decomposition requirements. In addition to the mathematical derivation we include an updated description of the algorithm. ¿ 1999 American Geophysical Union