AIM: To explore the reasons for screening failure of healthy subjects in clinical trials of orally inhaled drug products (OIDPs). METHODS: Screening data of 1 432 healthy subjects who participated in clinical trials of OIDPs were collected. The main reasons for the screening failure, gender differences in screening failure rate and the correlation between age and screening failure rate were summarized and analyzed. RESULTS: The screening failure rate was 72.4 % and increased with age. The failure rate was slightly higher in females than in males. Besides abnormal vital signs (17.3%), abnormal laboratory test results (16.5%) and withdrawal of consent (7.6%), poor venous condition (13.9%), positive for cigarette test results (12.6%) and failure in inhalation training (7.1%) were also the other three main reasons affecting the screening success rate. Abnormal vital signs and poor venous conditions were the primary screening failure reasons for males and females, respectively. CONCLUSION: The screening success rate could be improved by informing fully and communicating effectively, selecting young subjects with strong understanding abilities, and enhancing the training skills of investigators.