The present study was designed to evaluate the use of nanoparticles in improving the antiparasitic effect of Spiramycin, Spiramycin loaded on Carboxymethyl chitosan nanoparticles (CMC Np), ) on experimental toxoplasmosis. Different doses of the drugs under study were assessed using parasitological and histopathological investigations. For this purpose, a total of 38 female Swiss albino mice were divided as follows; Group 1 (5 mice) as a negative control group (non-infected, non-treated group). Group 2 (5 mice) as a positive control group (infected, non-treated group); Group 3: In this group, 28 mice were infected, and treatment started after 10-15 days post-infection for 1 week on a daily basis. The third group was subdivided into four subgroups (7 mice for each), which were treated as follows; subgroup (3a); the infected mice treated with Spiramycin alone in a dose of 100 mg/ kg /day orally, sub group (3b); the infected mice treated with CMC Np  orally.  Sub group (3c); the infected mice treated with Spiramycin loaded on CMC Np of concentration of 0.35 gm/100 ml H₂O (low dose-LD) orally. Subgroup (3d); the infected mice treated with Spiramycin loaded on CMC Np of concentration of 0.70 g/ 100 ml H₂O (High dose-HD) orally.  At the end of the experiment, liver and lung were dissected for detection of the parasite burden and the histopathological examination of the tissues was carried out to allocate the histopathological findings in these organs and detection of tissue cysts. Remarkably, a noticeable decrease in parasitic load was stated pooled with renovation of histopathological alterations were prominent with treated groups in association with infected non-treated group.