UNLABELLED: The general hypothesis of the study was to evaluate strategically important rural areas to confirm their characteristics of "excluded population" and identify the priorities to allocate human and financial resources of the international co-operation project. The aim of this study was to establish the degree of development of villages in the Trancas and Calchaqui valleys, and the oral health of children living in areas involved in an integral study on excluded villages in the northwest of Argentina. These villages are considered a priority in the UNIR Project; they are thus strategically important as a link with countries of the MERCOSUR. Data on living conditions were obtained through direct inquiries (Project UNIR, W. K. Kellogg Foundation/University of Tucumán) and from data supplied by the Ministry of Economy, by the Ministry of Culture and Education and by the SIEMPRO project of the Secretariat of Social Development of the Ministry of Health. The Human Development Index (HDI) was calculated as World Bank criteria (1995), The studies on dental conditions were carried out in all the children between 12 and 14 years old, that is a total of 58 in the Trancas Valley and 212 in the Calchaqui Valley. RESULTS: (1) The HDI was 0.731 for the province, 0.56 for the Trancas Valley and 0.51 for Calchaqui valley. (2) The results are above the values for the country in the first case, and below the average country values for the valleys. (3) The percentage of BNN families reached 92%. The results for oral health show: (4) the DMFT were 6.34 +/- 0.07 in the Trancas Valley and 7.47 +/- 0.276 in the Calchaquí valley. (5) Carious teeth (CT) were the most important component of this index. (6) The absence of a specific and preventive assistance. CONCLUSIONS: (a) Children between 12 and 14 living in the Valleys of Trancas and Calchaqui (Tucumán, Argentina) are affected by severe levels of caries, with values above the national and province means. (b) The human development index is below that of the corresponding national and province levels. (c) Inhabitants of these valleys can be identified as socially and biologically highly vulnerable. (d) The indicators of cariogenic risk reveal the importance of introducing oral preventive care components to the health plan for the area focused on the excluded population.