AbstractCost of production is considered an important economic factor that can refer to the efficiency of using resources. Due to the increase in prices of farm inputs and cost of farm operations, are of cultivated area of both faba beans and lintel crops has recently decreased. It is therefore, the objective of the present study to assess the effect of changes in production costs on the economies of faba beans and lentils crops. The main findings of the study are : * Cost of production of studied crops(faba beans and lentils) took an increasing trend estimated as 109.2 L.E and 104 L.E a year during the period 1990-2008 respectively. * Average costs of agricultural operations were 973 L.E and 995 L.E for faba beans and lentils in 2008 respectively. These costs represent about 48.3% and 51.4% of total variable costs of the two crops respectively. * Labor and machinery costs were the most effecting costs in farm operations, while costs of fertilizers and seed were the most effecting farm inputs for both the two crops. * Farm price for the two crops took an increasing trend estimated as 16.6L.E and 24.8 L.E a year during the period 1990-2008. Whole sale and retail prices have also taken an increasing trend during the same period. * As relation between production cost and farm price, the study reveals that a change of 10% of cash per ton of bean will lead to a change of 7.9% in farm price, while a change of lentil cost per ton of 10% will lead to a change in its farm price by about 6.9%. * The study concludes that there are no comparative advantage of both crops. * The study recommends that efforts should be made to decrease cost of local resources to increase the comparative advantage of such important legume crops.