Background This study evaluated the efficacy, safety, and acceptability of a new ferrous sulfate oral solution (Tardyferon® 20 mg/mL) in young children with mild or moderate iron deficiency anemia (IDA). Methods This was a multicenter, national, single‐arm, open‐label study. Children aged 6–53 months presenting with mild or moderate IDA (i.e., blood hemoglobin (Hb) ranging from 7.0 to 10.9 g/dL and serum ferritin <12 ng/mL) were eligible for inclusion. The ferrous sulfate heptahydrate solution (2 mg/kg/day) was administered orally for 3 months. If normalization of either Hb or ferritin was not achieved at month 3 the treatment was continued for another 3 months. Results Of the 100 children screened, 21 aged 6–17 months were included and received the study treatment, and 19 were analyzed for hematologic outcomes at month 3. Only one patient continued treatment for the additional 3 months. At month 3, mean ± SD Hb and ferritin levels were 12.0 ± 0.7 g/dL and 31.5 ± 19.4 ng/mL, respectively. Hemoglobin and ferritin levels were normalized in 95% (18/19) and 84% (16/19) of the patients, respectively. Treatment compliance and levels of satisfaction of both the parents and the investigators were high. Overall, 33.3% of patients (7/21) experienced at least one adverse event. Only one patient (4.8%) experienced a drug‐related adverse event (upper abdominal pain). Conclusions A 2 mg/kg daily dose of the new oral ferrous sulfate heptahydrate solution provides substantial therapeutic benefit with high levels of tolerability in young children who have mild or moderate IDA.