Harvesting high moisture grain and drying it on the farm has become a common practice in the Canadian prairies. Economic use of the drying facilities requires knowledge of the safe storage times of wheat at different storage conditions. In this work, emphasis was given to the determination of the deterioration rates of 19% moisture content (m.c., wet basis) wheat stored at constant temperatures of 35 to 10C in steps of 5C, and stored with a step decrease in the storage temperatures. The cultivar 'Barrie' was used for deterioration tests, because it is becoming the most popular cultivar in the Prairies. Safe storage times of grain stored with a step decrease in the storage temperatures were satisfactorily predicted except when the temperature was reduced from 30 to 20C. The safe storage times of 'Barrie' were lower than either 'Katepwa' or 'Domain'. Microflora were identified and free fatty acid values were determined when mould growth was visible for the first time. Mould growth became visible after the germination had dropped well below 90%. Free fatty acid values were high in high moisture content grain stored at high temperatures and increased with time due to the growth of microorganisms which hydrolysed the lipids in the grain. (Abstract shortened by UMI.)