Benjaminiella poitrasii is a zygomycetous, non-pathogenic dimorphic fungus. Chitin synthases are the membrane bound enzymes involved in the synthesis of chitin and are key enzymes in the cell wall metabolism. Multiplicity of these enzymes is a common occurrence. Here, we identify eight distinct CHS genes in B. poitrasii as confirmed through DNA sequence and Southern analysis. These genes are related to other fungal CHS genes. BpCHS1-4 are class I-III chitin synthases while BpCHS5-8 are class IV-V chitin synthases. These eight genes are differentially expressed during morphogenesis and under different growth conditions. Two of these genes viz. BpCHS2 and BpCHS3 appear to be specific to the mycelial growth form. These are the first B. poitrasii sequences to be reported. Based on CHS gene sequences, B. poitrasii chitin synthase genes place it with other zygomycetes on a fungal phylogenetic tree. (C) 2002 Elsevier Science (USA). All rights reserved.