The folacin and iron status of 193 adolescents from urban low-income households was evaluated. Red blood cell folacin concentrations were less than 140 ng/ml in 42% of the subjects and 140 to 159 ng/ml in 13%. Of the serum folacin values, 45% were less than 6 ng/ml, and 15% were below 3 ng/ml. Serum folacin levels decreased with increasing age (p less than 0.01) and sexual maturity (p less than 0.05). Transferrin saturation was low (less than 16%) in 12% of the females and 2% of the males. Transferrin saturation levels for females declined as age increased in contrast to an increase over age in males (p less than 0.01). Eleven percent of the females and 3% of the males were classified as anemic (less than 12 g/dl). Mean cell Hb concentration was low (less than 32%) in 24% of the females and 7% of the males. Of all subjects, 17% had low mean cell volumes (less than 81 mum 3). These findings demonstrate folacin and iron status is less than adequate in a significant proportion of this adolescent population group.