Iresine herbstii is fed to livestock in South-eastern Nigeria in the belief that it boosts their blood supply. The aim of this work is to study the effect of the methanolic extract of I. herbstii Hook on some blood parameters of experimentally induced anaemic albino rats. For acute toxicity study, graded doses of the methanolic leaf extract of I. herbstii at 10, 100, 1000, 1600, 2900 and 5000 mg/kg were administered orally to rats randomly allotted to six groups of three animals each and signs of toxicity were observed for 24 h. To evaluate its haematological effects, 100, 200, and 400 mg/kg of extract was administered orally to three out of five groups of six rats each for 14 days after the induction of acute blood loss anaemia. Parameters monitored were packed cell volume (PCV), haemoglobin concentration (Hb), weight gain and red blood cell counts (RBC). Phytochemical, proximate and nutritional analysis of the plant was done. I. herbstii had an LD50 > 5000 mg/kg. Mean group weight gain and RBC were significantly (p < 0.05) higher in treated than untreated groups. PCV and Hb did not differ significantly between the treated and untreated groups. Plant contained flavonoids; phenols; alkaloids; 22.85 % crude protein; 18.58 % ash; 9.62 % crude fibre; 1.5 % ether extract; 12.05 % moisture; vitamins A, C, E, B1, B3, B5, B6 and B12; zinc; iron; phosphorus; calcium; and magnesium. Methanolic extract of I. herbstii significantly improved red blood cell count of anaemic rats at the dose of 400 mg/kg bw and the body weights of anaemic rats at all treatment doses (100, 200 and 400 mg/kg bw).
