Trichomonads are flagellated protozoa that have occasionally been detected in the human respiratory tract, although detection rates have often been underestimated. We applied a nested PCR assay targeting the 18S rRNA gene of trichomonads to induced sputum from asthma patients to determine the prevalence of Trichomonas. Induced sputum was collected from 41 adults with asthma and analyzed through nested PCR using broad-range trichomonad primers and DNA sequencing for species identification. Nested PCR detected trichomonad DNA in 10 of the 41 (24.4%) samples. Sequencing and phylogenetic analysis revealed Trichomonas tenax in 8 cases and Tetratrichomonas sp. in 2 cases. These findings indicate that trichomonads can be present in the lower airways of patients with asthma, warranting further investigation into their clinical relevance.