Asexual sporulation (conidiation) in the ascomycetous filamentous fungi involves the formation of conidia, formed on specialized structures called conidiophores. Conidiation in filamentous fungi involves many common themes including spatial and temporal regulation of gene expression, specialized cellular differentiation, intra-/inter-cellular communications, and response to environmental factors. The commencement, progression and completion of conidiation are regulated by multiple positive and negative genetic elements that direct expression of genes required for proper vegetative growth and the assembly of the conidiophore and spore maturation. Light is one of the key environmental factors affecting conidiation. Developmental mechanisms in Aspergillus nidulans and Neurospora crassa have been intensively studied, leading to important outlines. Here, we summarize genetic control of conidiation including the light-responding mechanisms in the two model fungi. Copyright © 2012 Elsevier Ltd. All rights reserved.