In order to identify the effects of the kainic acid in the retina kainic acid (120 nmol/$5{mu}l$) were injected through the pars plana of the ciliary body into the duck eye ball at 7th day after hatching. The animals were sacrificed by decapitation on the 1st, 4th and 10th day after injection of the kainic acid. The specimen was processed for the light and electron microscopes respectively. The results obtained were as followings 1. The inner nuclear, inner plexiform and ganglion cell layers of the retina showed marked changes in all of the groups. 2. The cells in the inner nuclear layer showed marked degenerative changes of the organelles including the pyknoses and destruction of the nucleus on the 1st day after injection. These destructive changes of the cells were progressively disappeared until the 10th day after injection. 3. After injection of the kainic acid the neurites of the inner plexiform layer were swollen at the first, and thereafter those changes were gradually disappeared until the 10th day. 4. In the ganglion cell defected by the kinic acid, the enlargement and segmentation of the endoplasmic reticulum and pyknosis of the nucleus were-observed in all the groups, although the lipid droplets were only shown in the 4th day. From the above results, the evidence suggests that kainic acid gives to the toxic effect on the nuurons of the retina with exception of the photoreceptors.