Passenger car equivalents are used to represent the varying effects of mixed vehicle types on saturation flows by converting a traffic stream comprising of various vehicle types into an equivalent traffic stream comprising entirely of passenger cars. Procedures for signalized intersection analysis often recommend the use of measured saturation flow rates. However, it is impractical to measure prevailing saturation flow rate for an existing site and it is impossible to measure saturation flow rate for a new signal installation which is yet to be constructed. Hence, the development of a saturation prediction formula based on passenger car equivalents values derived according to local traffic conditions is necessary in order to estimate saturation flow rates accurately at signalized intersections. This paper discusses an investigation on passenger car equivalents and saturation flow rates for through vehicles at signalized intersections in Malaysia. The results obtained shows that the measured saturation flow rates are different from the values computed based on Highway Capacity Manuals in other countries such as U.S. and U.K. as the traffic compositions in Malaysia are different from those in developed countries.