colonization plays a key role in the progression of pulmonary infection. However, there are limited data regarding the colonization of these fungi in the patients residing in different regions of Iran. Regarding this, the present study was conducted to evaluate the prevalence of colonization in non-HIV-infected patients with respiratory failure introduced by physicians using nested polymerase chain reaction (PCR).This study was conducted on 136 samples obtained from 136 patients with respiratory disorders referring to different hospitals in the capital and north of Iran during 2013-2015. The samples were collected using bronchoalveolar lavage (BAL; n=121) and sputum induction (n=15). Nested PCR method targeting mtLSU rRNA gene was used for the detection of DNA in the specimens.The nested PCR analysis resulted in the detection of DNA in 32 (23.5%) patients. The mean age of the participants was 49.04±11.94 years (age range: 14-90 years). The results revealed no correlation between colonization and gender. The studied patients were divided into two groups of immunocompromised and immunocompetent patients. In the regard, 25.4% of the patients with detectable DNA were immunocompromised and had cancer, organ transplantation, asthma, sarcoidosis, dermatomyositis, chronic obstructive pulmonary disease, bronchiectasis, and pulmonary vasculitis. On the other hand, DNA was detected in 21.8% of the immunocompetent patients. Frequencies of DNA detection in the patients with tuberculosis, hydatid cyst, and unknown underlying diseases were obtained as 20.8%, 25%, and 22%, respectively. The prevalence of colonization varied based on age. In this regard, colonization was more prevalent in patients aged above 70 years.As the findings indicated, non-HIV-infected patients, especially the elderly, had a high prevalence of colonization. Therefore, these patients are probably a potential source of infection for others. Regarding this, it is of paramount importance to adopt monitoring and prophylactic measures to reduce this infection.