A study was designed to determine whether wheat could be substituted for corn without reducing yolk quality and yolk membrane strength. Diets with either corn or Florida 301 wheat as the grain source were fed to 50-wk-old hens (140 per diet). Eggs were collected and stored at 10 C for up to 4 wk or at 23 C for 1 wk. At weekly intervals Haugh units, yolk index, yolk rupture strength, and yolk deformation distance at rupture were measured and compression percentages were calculated. Haugh units and yolk index were not affected by diet. Yolk rupture strength and deformation were 12.3% and 4.7% greater, respectively, for eggs from hens on the wheat diet than for those from hens on the corn diet. Both rupture strength and deformation declined significantly with storage. Eggs stored at 23 C were lower in yolk rupture strength and deformation than those held at 10 C. Percentage of compression at rupture also declined with storage, but the decline was initially more rapid for egg yolks from birds fed the corn diet than for egg yolks from birds fed the wheat diet. It was concluded that Florida 301 wheat may be substituted for corn without incurring any problems in the quality of the yolk and that yolk breaking strength would be enhanced.