Two promlsmg varieties of soybean JS 335 (early maturing) and JS 80–21 (medium maturing) were halVested at physiological and physical maturity and heaped to a height of six feet. Observations on heap temperature, plant moisture, germination and vigour index from the plant of upper, middle and lower layers of the heap was recorded. Seed lots of plants harvested at physiological maturity deteriorated faster than the seeds harvested at physical maturity. The extent of deterioration was comparatively less in the medium maturing types. Heaping of the produce harvested definitely reduces the seed quality.