The objective of this study was to carry out a comparative study of the nutritional status of a representative sample of 651 rural school children from Chile's Metropolitan Region between two periods: 1986-1987 and 1989. The percentages of weight/age (%W/A), height/age (%H/A) and weight/height (%W/H), as well as Z scores were compared with WHO Tables; head circumference/age (%HC/A), with Tanner Tables and brachial anthropometric measurements with Frisuncho standards. Socioeconomic status (SES) was measured through Graffar's Modified Method. Statistical procedures included analysis of variance, "t" test for comparison of the means and chi-square. In 1989, results showed an improvement, both present nutritional status (%W/H) and SES as compared with 1986-1987 period. %W/A increased and %H/A decreased from 1986-1987 to 1989. %W/H should be a better indicator of nutritional status due to the high incidence of growth failure (47.4%) which was detected in 51.9% and 30.9% in low-low SES and medium SES, respectively (p < 0.001). Obesity was significantly higher in females (23.5%) than in males (13.2%) (p < 0.05) by which this problem must be prevented to avoid negative consequences in present and adult life. %HC/A positively and significantly increased from 1986-1987 to 1989 confirming that educational selectivity apparently relates to %HC/A, and not to %W/A or %H/A. Considering that only 13.0% of school-age children were beneficiaries of the School Feeding Program (PAE), the high prevalence of undernutrition and growth failure in non-beneficiaries and the fact that most part of the sample (86.9%) belong to low-SES, it should be necessary to increase the covering of PAE in the rural area of Chile's Metropolitan Region.