The study aims to estimate the aggregate index number for grain group prices in the production quantities during the period (2006-2011) as the base period and the period (2011-2015) as a comparative period. The results showed that the index lasper number was about 53% that of Bashy was about 54.3% that of Druobshy and Baly was about 35.75%, Fisher's index number was about 52.55% and the Marshall-Edgorth index number was about 53.59%. The results showed that Fisher's index number is the only one that achieves the condition of reflection in the coefficient and the reflection in the time, so it is characterized by high accuracy and quality of the estimate. The study also showed that the decline in the real value of money is the most important reason for the high level of inflation in the agricultural prices of grain crops. Therefore, the study recommends estimating s index numbers for prices of agricultural crops in Egypt should be based on Fisher's index number. The study also recommends adjusting the current prices of agricultural crops at constant prices to eliminate inflation, taking into consideration changing tastes, unequal changes in price levels for all members of the society, and changing the speed of money circulation due to changing purchasing habits of individuals. The study also recommends using a new year as the base year and not relying on an old year and encourage governmental corporations to produce accurate records.