The theory of fuzzy logics founded by Zadeh in 1965 has been proven to be useful for dealing with uncertain and vague information. The grey theory that was first proposed by Deng (1982) avoids the inherent defects of conventional statistical methods and only requires a limited amount of data to estimate the behavior of unknown systems. In this paper, we use the fuzzy set theory and the grey theory to develop an efficient method to predict the cash flows of an investment. The cash flows obtained are used in present worth analysis to determine if the investment is acceptable. Illustrative examples are given.