Maize is an important cash crop of the country, for both the domestic consumption as animal feed and export. It is therefore necessary to improve production efficiency and quality of Maize in order to meet local and export demands. The Seventh National Economic and Social Development Plan Promotes the use of good varieties to increase Maize Production in Thailand. The objective of this study is to analyze this economics of maize production in Prachin Buri Province in 1991/92 Crop Year by estimating production function, technical and economic efficiency of input use. In addition cost and return analysis of maize production classified by hybrid and Suwan varieties obtained from 104 maize growers was all analyzed. Cobb-Douglas production function was employed to analyze the relationships between maize yield and farm input namely labor Explicit Costs for fertilizer, chemicals and varieties used. The result of the analysis revealed that all farm inputs significantly determined maize yield with elasticities for hybrid and Suwan Varieties of 0.2635, 0.2311 and 0.4221, 0.8355 for cash expenses and labor respectively. The economic efficiency of input used showed that both groups of farmers who used hybrid and Suwan Varieties should increase the use of cost expenses and labor in order to obtain maximum profit. The cost and return analysis showed that total cost of production of the farmers who used hybrid variety was higher than Suwan Variety at B937.51/rai compared to B654.86. However, due to higher yield in hybrid variety,the net return from using hybrid was B604.43/rai compared to B418.96/rai of Suwan Variety. In conclusion, the use of good need varies in conjunction with good management and appropriate level of inputs used will definitely increase maize yield, reduce cost per unit and increase farm income.