The effects of Spirulina platensis and Panax ginseng dietary supplementations were analysed in 30 female adult Wistar albino rats divided in 3 equal groups. In the first and second groups, animals were treated with Spirulina platensis (300 mg/kg/day) and with Panax ginseng (400 mg/kg/day) respectively in drinking water for 30 days, whereas the third group served as control. Red Blood Cell (RBC) and White Blood Cell (WBC) counts, numeration of leukocyte types, Packed Cell Volume (PCV) and haemoglobin concentrations were determined by haemocytometric methods on blood samples collected on days 0, 15 and 30, and Mean Globular Volumes (MGV) and Mean Corpuscular Haemoglobin Concentrations (MCHC) were calculated. Populations of B and T lymphocytes were counted by the proportional to naphthyl acetate esterase (ANAE) staining method. Spirulina platensis and Panax ginseng treatments markedly stimulated the erythrocyte formation and the haemoglobin synthesis on day 30 and small erythrocytes (microcytosis) greatly loaded with haemoglobin (increases of MCHC) were obtained especially with Panax ginseng. Dramatic increases of WBC counts since the 15th day were also observed in both treated groups. In Spirulina- treated rats, the neutrophil count was enhanced precociously (since the 15(th) day). The overall lymphocyte population as well the T cell number has gradually augmented according to the treatment duration in all treated rats. Furthermore, Panax ginseng treatment has exhibited significant greater effects on lymphocyte and T cell counts than Spirulina platensis treatment. These results suggest that these 2 biomedicines positively interfere with bone marrow cellular production and with immune cellular response and may be useful as adjuvant treatment of anaemia or of immune deficiency.