Parasitic diseases are among the most serious public health problems in developing countries, causing high mortality and economic burdens. The Trypanosomatidae family includes Leishmania spp. and Trypanosoma cruzi, which cause leishmaniasis and Chagas disease, respectively. Both these parasites are among the major agents of neglected tropical diseases (NTDs). Leishmaniasis is currently the second most widespread vector-borne parasitic disease after malaria. The World Health Organization (WHO) records approximately 0.7-1 million newly diagnosed leishmaniasis cases each year, resulting in approximately 20,000-30,000 deaths. Also, 25 million people worldwide are at risk of Chagas disease and an estimated 6 million people are infected with Trypanosoma cruzi. Despite the similarity of the parasites, the evolution of the disease and the clinical indexes are explicitly different in African, Asian, and American forms of infection. Clinical therapies are associated with drug resistance and side effects. As a result, the discovery of novel therapeutic agents has emerged as a top priority and a promising alternative. Peptide-based drugs are an attractive class of therapeutic agents. They are recognized for being highly selective and effective, as well as safe and well tolerated. Moreover, they are now being explored in the development of novel therapeutics for a variety of health disorders, including oncology, endocrinology, metabolic, cardiovascular, and bone diseases. In addition, they are being explored in tropical diseases such as leishmaniasis and Chagas disease. We will discuss current knowledge regarding the parasite life cycle, signs and symptoms, diagnosis, and treatment options for leishmaniasis and Chagas disease.