Introduction: Study to evaluate the pharmacokinetics (PK), subject satisfaction, and gastrointestinal (GI) tolerability of single and multiple doses of a novel oral iron formulation based on iron enriched microalgae Spirulina platensis supplemented with inactivated yeast. Methods: Twelve healthy women with baseline serum iron 4-12 mol/L (22.3-67.0 g/dL) were admitted to the study site for 3 days in this single centre, multiple-dose, open-label study. Subjects received an oral dose of Monurelle(R) Ferro Naturale (MFN) on Days 1, 2, and 3. Blood for PK analysis was collected pre-dose (0) and at 1, 2, 3, 4, 5, 8 hours after dosing on Days 1 and 3, with assessment of subject satisfaction and GI tolerability performed 3 hours after each dose. Results: Both single and multiple dosing with MFN led to a defined peak level (Cmax) and increased systemic exposure (AUC0-t), with serum iron rising to almost double the circulating amount at 5 h post-dose (tmax). Mean ({+/-}SD) percent change from baseline at 5 h post-dose was 94.7% ({+/-}56.1) on Day 1 and 72.0% ({+/-}70.7) on Day 3. The majority of subjects reported being satisfied with the product and would use it again in the future. MFN was very well tolerated, with only one adverse event (AE) reported (episode of vomiting after the first dose, that lasted for one minute and did not recur after the two further doses of MFN). No other subject experienced any GI side effects. Discussion: This first report of oral Monurelle(R) Ferro Naturale in humans shows this novel formulation to provide a favourable PK profile with respect to serum iron concentrations, with excellent tolerability and high subject satisfaction.