Background: Nowadays, nanocarriers are used for leishmaniasis treatment due to development of drug resistance and several side effects with conventional therapeutics. Objectives: In this study we aimed to evaluate in vivo effects of four synthesized nanodrugs including amphotericin B-nanochitosan (AK), betulinic acid-nanochitosan (BK), amphotericin B-dendrimer (AD), and betulinic acid-dendrimer (BD) in the treatment of Leishmania major infection (L. major) in mice model by using pathological analyses to choose the most effective nanodrug in leishmaniasis. Methods: The four nanodrugs efficacy in the improvement of L. major lesion in a mice model was evaluated by using pathological analyses including measurement of organs size and parasite number. Additionally, the nanodrugs toxicity was evaluated by measurement of various blood factors. Results: The histopathological results of the present study showed that BK, at the dose of 20 mg/kg, and AK, at the dose of 10 mg/kg, were more effective in decreasing the parasite number in the kidney, liver, and spleen. Moreover, BK20 mg/kg and AK10 mg/kg decreased the organs size significantly while AD50 mg/kg and BD40 mg/kg were less effective. However, none of the four nanodrugs had increased the blood factors and they were not toxic. Conclusions: Overall, the pathologic findings of various mice organs treated with different formulations showed that AK10 mg/kg and BK20 mg/kg were more effective in recovery of L. major's pathological effects in comparison to AD50 mg/kg and BD40 mg/kg. Therefore, it seems that AK and BK, in this mentioned dosage, could be considered as a proper candidate for treatment of leishmaniasis.