Twenty one wheat and corn based food products elaborated in Costa Rica were analyzed by chemically with the purpose of having data on local foods. The analytical methods to determine proximate composition were AOAC's. Energy was estimated by calorimetric bomb and dietary fiber (DF) by the gravimetric enzymatic method. Also food portion size was estimated and related with DF content for food classification. The values of the nutrients per food were established and compared with others reported in foreign tables commonly used in the country. Fat and energy content in cookies are higher than in salad breads and crackers. Wheat and corn based food products are classified either as low or very low DF sources (< 2.9 g FD/portion). Corn "tortilla" DF content duplicates bread's and the fiber is basically insoluble. Marked differences were founded in the nutritive composition of specific foods when compared with values reported in foreign food tables. In other foods, as corn based products, similarities in the chemical composition were common. The chemical composition of the studied local foods shows the potential of the diet to be atherogenic, an important aspect to be considered with relation to the main causes of mortality in Costa Rica population. The more compatible food composition table with our data is the Central American, followed by the Latin American one. The necessity of having data on the chemical composition of local foods has been demonstrated.