A random sample group of 300 children and adolescents (aged 0.5 to 16 years) from a Mediterranean town of Spain, were investigated as part of a health education program. Analysis of dietary iron intake and the biochemical parameters of iron status (red cell volume, erythrocyte protoporphyrin concentration, transferrin saturation percentage and serum ferritin) were measured. Based on dietary assessment, the percentage of children with iron intake levels below the Catalonia Recommended Daily Amounts varied from 24% to 77% and showed age and sex differences. The percentage of children with iron intakes below their own individual requirements varied between 7% and 41%. The age groups with the highest risk of iron deficiency were girls aged between 6 and 24 months, and boys aged between 13 and 16 years. However, based on the biochemically assessed iron status, the results revealed an overall prevalence of iron deficiency varying from 0 to 23.3%. The highest prevalence was encountered in boys and girls between 6 and 24 months (23.3%), compared with only 3.3% between 13 and 16 years. Despite conducting the investigation with the recommended controlled methodology, the results from dietary assessed risk of iron deficiency were significantly different from those assessed biochemically. Hence, caution is required when designing health programme strategies based exclusively on nutritional intake assessments.