Neurospora crassa is the best-understood fungal organism in terms of the mechanism of light responses. All known Neurospora photoresponses are mediated by blue light. Two Per-Arnt-Simdomain containing transcription factors, WHITE COLLAR-1 (WC-1) and WC-2, are essential components for almost all light responses. Recently, WC-1was shown to be a blue-light photoreceptor. How light affects the DNA binding of the WC proteins to the promoter of the circadian clock gene frequency was also demonstrated. These studies established a mechanism that explains the light responses mediated by activation of transcription. The purpose of this review is to summarize the findings of recent studies on the molecular mechanism of photoreception in Neurospora.