The time of synthesis, the molecular weight, and the relative glutamine-glutamate and proline to leucine ratios of the endosperm proteins of wheat (Triticum aestivum L. cv. Logan) were determined using a sodium dodecyl sulfate-polyacrylamide gel technique. In general, synthesis of most proteins occurred through much of the maturation of the seed, but past 20 days the rate of synthesis of the high molecular weight proteins declined more rapidly than those of lower molecular weight. The synthesis of at least one protein occurred only late in seed maturation. Several of the high molecular weight proteins had glutamate-glutamine to leucine ratios higher than the remainder of the proteins. No evidence for proteins of a polyglutamine-glutamate and/or proline nature was found.