Light signals constitute major factors in regulating gene expression and morphogenesis in plants and fungi. Phytochrome A and B were well characterized red and far-red light receptors in plants. Red light signals increased the phosphorylation of 18 kDa protein, which was identified to be nucleoside diphosphate (NDP) kinase. The NDP kinase catalyzed autophosphorylation and had a protein kinase activity similar to MAP (mitogen activated protein) kinase. As candidates for blue light photoreceptors, cDNAs for CRY1 and CRY2 were isolated. The N-teminal regions of these proteins showed a high hornology to DNA photolyase. The 120 kDa protein first detected in Pisurn sativurn, which showed blue light induced phosphorylation was also detected in Arabidopsis thaliana. The 120 kDa protein was encoded by the nphl gene, which regulated positive phototropism of the plant. In Neurospora crassa, blue light irradiation of the membrane fraction prepared from roycelia stimulated the phosphorylation of the 15 kDa protein, which was also identifmd to be an NDP kinase. Recent progress in understanding early events in light signal transduction mainly in Pisum sativum Alaska, Arabidopsis thaliana and Neurospora crassa was summarized.