Malaria is an infectious disease responsible for approximately one million deaths annually. The antimalarial effects of angiotensin II and its analogs against Plasmodium gallinaceum and P. falciparum have recently been reported. To evaluate anti-plasmodial activity, we synthesized five angiotensin II restricted analogs that containing disulfide bridges. To accomplish this, peptides containing two inserted amino acid residues (cysteine), were synthesized by the Fmoc solid phase method, purified by liquid chromatography, and characterized by mass spectrometry. Conformational studies were performed by circular dichroism. The results indicated that two of the analogs had higher anti-plasmodium activity (92% and 98% activity) than angiotensin II (88% activity), measured by fluorescence microscopy. Results showed that the insertion position must be selected, to preserve the hydrophobic interactions between the nonpolar residues, as this affects anti-plasmodial activity. The circular dichroism studies suggested that the active analogs as well as the native angiotensin II adopt a β-turn conformation in different solutions. This approach provided insight for understanding the effects of restricting the ring size and position on the bioactivity of angiotensin II and provides a new direction for the design of potential chemotherapeutic agents. This article is protected by copyright. All rights reserved.