Abstract: Toxoplasmosis is one of the widest spread parasitic infections which is caused by Toxoplasma gondii protozoon. Many experimental studies have evaluated the effect of aminoguanidine upon parasitic load and inflammatory process. However, few reports have illustrated the impact of combining aminoguanidine with spiramycin in the treatment of toxoplasmosis. Therefore, our study aimed to explore the possible effects of spiramycin used alone and combined with aminoguanidine against the avirulent (ME49) Toxoplasma gondii strain in experimental toxoplasmosis. Fifty-five Swiss albino mice were included in the study and were divided into five groups: (GI): noninfected control group; (GII): infected untreated control group; (GIII): infected- spiramycin treated group; (GIV): infected-aminoguanidine treated group; (GV): infected and received combination of spiramycin and aminoguanidine. Obtained results exhibited a significant increase in brain cysts numbers in aminoguanidine treated groups compared to infected untreated control groups. Histopathological studies denoted that combination between spiramycin and aminoguanidine improved the pathological features only in liver and heart tissues of the studied groups. Moreover, it was noticed that spiramycin administered alone had no effect on nitric oxide expression, whereas its combination with aminoguanidine had an inhibitory effect on inducible nitric oxide synthase enzyme in brain, liver and heart tissue of different study groups. In conclusion, combination of spiramycin and aminoguanidine significantly reduced the parasitic burden, yet, it failed to resolve the pathological sequels in brain tissues of Toxoplasma gondii infected mice. Keywords Toxoplasmosis  Nitric oxide  Aminoguanidine  Spiramycin