This study reports on a new parasite of the digestive gland of the queen conch, Strombus gigas. An intense and generalized sporozoan infection was detected during a reproductive study of S. gigas in San Andres island (Colombia). The parasite was found in the digestive gland of every sampled S. gigas, with a heavy intensity of infection (invasion of every cell) in many animals. The infection of the digestive gland began in the cryptic cells and later secretory cells were also infected, giving way to discharge of sporocysts to the stomach through the digestive gland ducts. Apicomplexa-like trophozoites were embedded in the digestive gland epithelial cells and attached to host cell wall by their conoid end. Several stages were detected: trophozoites, sporocysts, and gamonts containing macrogametes or microgametes. Given the presence of multiple stages at the same time, the entire life cycle of the parasite is assumed to occur within the same host and tissue. The taxonomic position of the parasite should be ascertained by DNA analysis.