Iron deficiency without anemia can be manifested by a multitude of neurologic symptoms, including periodic limb movements of sleep (PLMS). Symptoms improve with Fe supplements. We undertook an investigation of children with PLMS on polysomnogram and of children without evidence of abnormal sleep by detailed history and screening questionnaire. After obtaining 3‐day diet record and baseline biomarkers, 2 mg oral stable isotope (58Fe) was administered fasting to measure Fe absorption by RBC enrichment after at least 3 months without Fe supplementation. Results for 2 controls (females, 14.0 ± 0.2 yrs) and 3 study subjects (2 M, 1F, 8.0 ± 1.5 yrs), respectively: dietary Fe (%RDA) 124.2 ± 62.5 and 122.4 ± 38.5; hemoglobin (g/L) 143 ± 4.2 and 136 ± 3.1; serum ferritin (μg/L) 33.4 ± 0.8 and 44.7 ± 4.2; Fe saturation (%) 24.5 ± 4.9 and 24.7 ± 11.7; free erythrocyte protoporphyrin 5 ± 0 and 8 ± 5.7. Fe absorption by RBC enrichment is currently being analyzed for both groups. Conclusion: Fe intakes in these children appear adequate although there are no data regarding heme Fe vs non‐heme Fe. Serum ferritins are in the low normal range. Further conclusions may be made after the RBC enrichment results are complete. Supported by NIH #DK07658 – T32 and Pediatric CTRC, NIH # M01 RR00069