The induction of PAL in Rhodotorula glutinis and transformation of L-phenylalanine from trans-cinnamic acid were studied. The optimum medium for PAL induction was composed of (g/L) 10.0 yeast extract, 10.0 peptone, 5.0 NaCl, 0.5 KH2 PO4, 0.5 phenylalanine 1.0 (NH4)2SO4 and 5.0 glucose, pH 6.0-6.5. The cultivation temperature was 30.0 degrees C. In the process of transformation, the effect of [NH4]+ on initial velocity was in accordance with Michaelis-Menten rate expression in which Km and Vmax were 16.85 mol/L and 5.96 g.L-1.h-1 for ammonia and the optimum pH was 10.0. Substrate activation and inhibition were observed at low and high concentration of cinnamic acid. The yield of phenylalanine from cinnamic acid reached more than 60.0%.