Aim of the study: To evaluate semen parameters and to assess serum FSH, LH, Testosterone (T) concentrations before and 12 weeks after intravenous iron therapy (800-1200 mg elemental iron therapy - IVI) in adults with iron-deficiency anemia (IDA). Materials and Methods: We studied 11 eugonadal adults with IDA, aged 40 ± 5 years, due to defective intake of iron. Anemia was diagnosed when hemoglobin (Hb) was equal or below 10 g/dl. Serum iron, total iron-binding capacity (TIBC) and ferritin concentrations confirmed the diagnosis of IDA. Basal serum concentrations of FSH, LH, and T were measured. Semen parameters were evaluated before and 6-7 weeks after IVI therapy. Results: After IVI therapy and correction of anemia, a significant increase of Hb from 8.1 ± 1.17 g/dL to 13.1 ± 0.7 g/dL was observed and was associated with an increase of T (from 12.22 ± 1.4 nmol/L to 15.9 ± 0.96 nmol/L; P < 0.001), FSH (from 2.82 ± 0.87 to 3.82 ± 1.08 IU/L; P = 0.007), and LH (from 2.27 ± 0.9 to 3.82 ± 1.5 IU/L; P = 0.0002). Total sperm count (TSC) increased significantly from 72 ± 17.5 million/ml to 158 ± 49 million/mL (P < 0.001), rapid progressive sperm motility (RPM) increased from 22 ± 9.4 to 69 ± 30 million/ml (P < 0.001), and sperms with normal morphology (NM) increased from 33 ± 5 to 56 ± 7 million/ml (P < 0.001). Increment in Hb concentration was correlated significantly with LH, FSH, and T concentrations after IVI (r = 0.69 and r = 0.44, r = 0.75, respectively; P < 0.01). The increment in serum T was correlated significantly with increments in the TSC and total sperm motility and RPM (r = 0.66, 0.43, and 0.55, respectively; P < 0.001) but not with gonadotrophin levels. Conclusion: Our study proved for the first time, to our knowledge, that correction of IDA with IVI is associated with significant enhancement of sperm parameters and increased concentrations of serum LH, FSH, and T. These effects on spermatogenesis are reached by an unknown mechanism and suggest a number of pathways that need further human and/or experimental studies.