Harvesting of a fruit is the beginning of loss in weight and firmness. Measuring changes in weight require maintaining identity of the fruit and current methods used to measure firmness are usually destructive. Alternative methods are needed which can rapidly and nondestructively sense fruit quality. Three cultivars of peaches were measured during 9 days of storage to obtain fruit having varying weight loss and firmness. The average daily whole fruit weight losses were 1.72, 2.19, and 2.22% for 'Garnet', 'Red Haven', and 'Sentinal', respectively. After 9 days of storage, the water content of the outer layers of a peach were less than at the center. Firmness, slope of the force-deformation curve obtained during 1 mm compression, decreased significantly during the first 3 days of storage and continued to decrease but by a smaller amount thereafter. By eliminating the time variable, firmness exponentially decreased with weight loss with an r of 0.79-0.88. Changes in water content and firmness of the outer layers appear to be good predictors of subsequent changes in the whole fruit.