In cancer patients mild-moderate non-chemotherapy-induced iron deficiency anemia (IDA) is usually treated with oral iron salts, mostly ferrous sulfate. In this study, we compare efficacy and toxicity of oral ferrous bisglycinate chelate and ferrous sulfate in cancer patients with mild IDA. Twenty-four patients operated on for solid tumors (10 breast, 12 colorectal, 2 gastric), aged 61±10years (range 45–75), with non-chemotherapy-induced hemoglobin (Hb) values between 10 and 12g/dL and ferritin lower than 30ng/mL were randomized to receive oral ferrous bisglycinate chelate, 28mg per day for 20days, and then 14mg per day for 40days (12 patients) (A group) or oral ferrous sulphate, 105mg per day for 60days (12 patients) (B group). Values of hemoglobin and ferritin obtained at diagnosis, 1 and 2months from the beginning of treatment were compared. Adverse events (AEs) related to the two treatments were recorded. In the 12 patients treated with ferrous bisglycinate chelate, basal hemoglobin and ferritin values (mean±SD) were 11.6±0.8g/dL and 16.1±8.0ng/mL. After 2months of treatment, they were 13.0±1.4g/dL and 33.8±22.0ng/mL, respectively (P=0.0003 and P=0.020). In the group treated with ferrous sulphate, hemoglobin and ferritin mean values were 11.3±0.6g/dL and 19.0±6.4ng/mL basally, and 12.7±0.70g/dL and 40.8±28.1ng/mL (P<0.0001 and P=0.017) after 2months of treatment. AEs occurred in six cases. In all these six cases, two (17%) treated with ferrous bisglycinate chelate and four (33%) with ferrous sulphate, toxicity was grade 1. In conclusion, these data suggest that ferrous bisglycinate chelate has similar efficacy and likely lower GI toxicity than ferrous sulphate given at the conventional dose of 105mg per day for the same time.