Cloned myo-inositol-1-phosphate synthase (INOS) of Drosophila melanogaster was expressed in Escherichia coli, and purified using a His-affinity column. The purified INOS required NAD$^$+/ for the conversion of glucose-6-phosphate to inositol-1-phosphate. The optimum pH for myo-inositol-1-phosphate synthase is 7.5, and the maximum activity was measured at 40$^{circ}C$. The molecular weight of the native enzyme, as determined by gel filtration, was approximately M$\_$r/ 271,000${pm}$15,000. A single subunit of approximately M$\_$r/ 62,000${pm}$5,000 was detected upon SDS-polyacrylamide gel electrophoresis. The Michaelis ($K_{m}$) and dissociation constants for glucose-6-phosphate were 3.5 and 3.7 mM, whereas for the cofactor NAD$^$+/ these were 0.42 and 0.4 mM, respectively.