SUMMARY   The retina is the photoreceptor organ and is divided into ten layers which contain the neuronal elements (photoreceptor, bipolar, and ganglion cells). Monosodium glutamate is a widely used food additive as it enters in the preparation of many food types. It is the salt of glutamic acid, which is a non essential amino acid that can be synthesized in the human tissue. The aim of the present work is to detect the early and delayed effects of monosodium glutamate on the retina of neonatal albino rats by using histological and ultra structural techniques. A total number of 24 animals aged 2 days postnatal were used in this study. Twelve animals were used as controls and injected with saline. The other 12 animals were treated subcutaneously with 4mg/gm body weight monosodium glutamate from the 2^nd to the 18^th day postnatal. The retina of six treated animals was examined in the next day after the last dose of treatment to detect the early effect of monosodium glutamate administration. The retina of the remaining six of the treated animals was examined later on at the age of 2 months to detect the delayed effect of monosodium glutamate. The semi-thin sections showed significant reduction in the thickness of different layers of the retina of the treated groups as compared with the control. This reduction was more marked in the treated 2 months age group as compared with the treated 19 days age group. This reduction in the thickness was detected by using statistical analysis using student t-test. On the ultra structural level manifestation of degeneration and cell death are observed in the treated groups. These include distortion in the shapes and dimensions of the cells and nuclei, marked vacuolization of the cytoplasm and destruction of the cell organelles. These monosodium glutamate induced ultra structural changes were prominent in the inner nuclear layer as well as in the ganglionic cell layer. Also these changes were more obvious in the older animals. It is concluded that monosodium glutamate has a toxic effect on different layers of the retina. This effect was more marked in the inner nuclear and ganglionic cell layers. In addition the late effect was more marked than the early effect.