Conjugates of gold nanoparticles and antibodies have useful functionalities. Here, we show how they can be used to selectively target and destroy parasitic protozoans. Gold nanorods were conjugated with an anti-Toxoplasma gondii antibody and used to target the extracellular tachyzoite which is an infectious form of an obligate parasite Toxoplasma gondii. Subsequent laser irradiation was used to kill the targeted protozoans. This concept provides a new paradigm for the treatment of parasitic protozoans.