Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite of adverse effect on fetus and immunocompromised host. The potential therapeutic effect of spiramycin- loaded poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) was evaluated for treatment of acute murine Toxoplasmosis. Fifty Swiss albino mice were grouped into five (ten each). Groups 1 and 2 were kept as untreated controls, negative and positive, respectively. Tested mice were subcutaneously injected by the virulent RH strain of T. gondii (103 tachyzoite/ mouse) and simultaneously treated by spirmycin alone (group 3), PLGA alone (group 4) and spiramycin loaded PLGA (group 5). The treatment lasted for 7 consecutive days. Spirmycin was administered in doses of 200 mg/kg/ body weight once daily while 200μg/kg/day was the dose for PLGA (groups 4 and 5). On the seventh day post infection the animals were sacrificed for evaluation. The toxicity induced by the treatment was estimated by measuring reduced glutathione (GSH) and malondialdehyde (MDA) in different tissues. The immune response associated with the treatment was estimated by measuring interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α) and IgM in serum samples. In comparison to the infected groups (non-treated, spiramycin treated and PLGANPs treated) spiramycin loaded PLGANPs showed a significant reduction in the number of tachyzoites (P < 0.05) in peritoneal fluid, liver and spleen, achieved the significant least toxicity of the tissues (liver, kidney and intestine) as reflected by mean levels of GSH and MDA levels. In spite of significant raising of the mean level of IFN-γ (P < 0.05) in group 5, however the mean levels of IgM, TNF-α were significantly reduced (P < 0.05). This study supports the role of PLGANPs in the optimal performance of spiramycin and confirms its efficiency in achieving treatment of murine toxoplasmosis.