Background: Lead is a toxic heavy metal extensive in the environment. Lead induces oxidative stress. mesenchymal stem cells (MSCs) have multiplied great attention as an efficient tool in regenerative therapy. Flaxseed oil (FSO) natural source of antioxidant agents which reduced oxidative stress.Aims: The current study purposes to explore the effects of MSCs and FSO on the toxicity of lead acetate on haematological parameters. Material and methods: Forty rats were randomly divided into four groups and 10 rats per group. Group (1): healthy normal group, group (2): rats injected with lead acetate (100 mg/kg b.w.t./intraperitoneal injection) for seven days. group (3): rats were treated with a single dose of bone marrow mesenchymal stem cells (1 × 10⁶ cells/rats) intravenously injected after lead intoxication. group (4): rats were given orally flax seeds oil (1ml/kg) for 30 days after lead intoxication. After the experiment, all rats were euthanized and collected blood for the examination of blood parameters. Results: Lead acetate induces a reduction in RBCs, Hb concentration and PCV. Also, lead increases WBCs count, lymphocytes, monocytes, neutrophils, eosinophils, MCV, MCH, MCHC and platelets. Although, MSCs and FSO improved all haematological blood. Conclusions: MSCs and FSO proved to have a powerful effect on the toxicity of lead acetate in the hematopoietic system.