Background . This article presents the results of a study aimed at Assessing food and nutritional security (FNS) in the Cesar department (middle Magdalena area of Colombia) carried out by Corporacion Obusinga and the Observatorio de Seguridad Alimentaria y Nutricional (OBSAN) which was financed by Corporacion Obusinga and the Medicine Faculty at the Universidad Nacional de Colombia (UNALCO). It also formed part of action involved in a Project for the participative construction of a proposal for territorial development having a food-based perspective in 12 towns in the Cesar department. Objective . This study was focused on determining the level of food and nutritional insecurity of the population living in 12 towns in the south of the Cesar department. Materials and methods . This study was based on references provided by the Instituto de Nutricion de Centroamerica y Panama (INCAP). The methodology used had been designed for food basket studies by UNALCO in 2003 and was adapted by Corporacion Obusinga for this study in the middle Magdalena area. Results . This investigation led to researchers recognising some of the target population's sociodemographic characteristics, identifying the basic food basket for the selected towns, establishing the usual food basket and recommended food basket for each town and household deprivation and poverty lines. Conclusions . The importance of such results lay in revealing the high levels of food insecurity amongst people from the selected towns in the south of the Cesar department which were reflected in inadequate levels of calorie and nutrient intake and the high percentage of households below the deprivation and poverty lines, thereby becoming a basic tool for orientating the formulation or adjustment of local FNS plans in the region.