Infections with protozoans, mainly due to immunodeficiency, are common all over the world. However, pulmonary infections with protozoans are less frequent. Lophomonas sp. is a flagellated protozoan that lives in the gastrointestinal tract of some species of cockroaches. Some cases, that show the presence of Lophomonas in populations whose lungs are affected, have been reported. Case report: The medical records of nine patients were studied: seven adult patients and two pediatric patients who were in the Intensive Care Unit (ICU) and in the Neonatal Intensive Care Unit (NICU), respectively. The samples were taken from tracheal aspirations and bronchoalveolar lavages. The patients’ ages were between 9 and 95 years, and 60% of them were male. Some of the patients were healthy, a priori, and others were immunosuppressed. There were found three patients with neoplasia, two patients with diabetes mellitus and four patients with no systemic pathologies. It is concluded that Lophomonas sp. is a protozoa parasite which emerges from the upper and lower respiratory tract of hospitalized patients. However, its pathogenic role is still controversial in all cases, that's why it merits further study for its understanding and possible treatment.