ten-a is one of the two Drosophila genes whose products belong to the Ten M protein family. The Ten-a protein is a type II transmembrane protein. This protein was found to be mainly expressed in the CNS of the embryo and in the compound eye of the pupa. No report about the function of ten-a has been published to date. Here, we showed, in a preliminary report, that ten-a has a function in the development of the CNS and in the compound eye. To study the function of ten-a during CNS development, doublestranded RNA interference (dsRNAi) experiments were performed. We found that embryos without Ten-a protein have defects in the commissures, suggesting that ten-a is likely to be involved in commissure formation. Furthermore, to study the function of ten-a in the eye, the Gal4/UAS system was used to overexpress ten-a at different stages of eye development. We found that extra amounts of Ten-a can interfere with the development of the eye. Flies overexpressing ten-a showed eye defects such as small and rough eyes, and black ommatidia. The results indicated that ten-a may be a novel gene involved in eye morphogenesis.