Drosophila rhodopsin (Rh1) is the visual pigment of the photoreceptor cells. It is synthesized in the ER after which it undergoes post-translational modifications before being transported to the rhabdomere where it functions in phototransduction. In this study, I describe the identification of the Drosophila ninaG gene that affects rhodopsin content in the photoreceptors. Using deficiencies and P-element induced deletions, the ninaG gene was mapped to 86E4-86E6 cytological region on the third chromosome. Sequencing analysis of all fifteen genes within this region identified a stop codon in CG6728 gene in ninaGP330 mutant. To confirm this identification, I rescued the ninaG phenotype with a genomic fragment containing CG6728 ORF. CG6728 belongs to the glucose-methanol-choline (GMC) oxidoreductase family. NinaG protein is required in the eye for the transport of Rh1 from the ER to the rhabdomeres. My results show a specific and post-transcriptional role for NinaG in the biogenesis of Drosophila rhodopsin.