To investigate the mechanism for the main chain-elongation process and the possibility of putative precursors as stater units in the biosynthesis of the Monascus pigments, feeding experiments with possible poly-β-ketide intermediates were carried out. Both crotonic acid and sorbic acid. especially In low concentrations, enhanced the pigment production while not increasing the dried mycelium weight appreciably. Also, it was observed that the feeding of sorbic acid and its ethyl ester was about two folds efficient in the pigment production than the feeding of crotonic acid and its ethyl ester. In addition to these acids, cinnamic acid and vinylacrylic acid were examined for their possibility as starter units. It was observed that the color of the culture fed with cinnamic acid was dominantly dark-red, but with overall decrease in the pigment production. Whey its ethyl ester was administered to the culture. however, the pigment production increased significantly. Also noted in 2D TLC study o1 the pigments was the increased production of red pigment and the formation of new red pigments.