To lower the pressure of nasal CPAP is one of the critical issues of improving patients’ acceptance and compliance. This study was designed to compare the effects of Herba Schizonepetae and nasal steroid on OSAHS patients with CPAP treatment.Male patients with moderate to severe OSAHS, excluded anatomical abnormalities of nose, throat and oral cavity, were recruited and divided into 2 groups. Subjects in the Herba Schizonepetae (HS) group, boiled twice a day, nasally breathed in the herbal steam before orally took the decoction. Subjects in the nasal steroid (NS) group used the steroid twice a day for the first 5days, and then once a day for the following day. Measurement including CPAP pressures, SaO2, AHI, and Visual Analogue Scale (VAS) of nasal ventilation conditions were recorded. Baseline data were collected when all subjects continued their effective CPAP treatment every night for 2weeks. Each group stopped CPAP and only used nasal interventions for 2weeks. After that, all subjects took their CPAP treatment as before for 2 continuous nights, where data were collected as post-treatment measurements.56 subjects (31 in HS group and 25 in NS group) completed the whole study. In the HS group, pre- and post-treatment pressure were 10.45±2.26cm H 2 O and 9.19±2.06cm H 2 O respectively. In the NS group, that were 10.27±2.10cm H 2 O and 9.03±2.11 cm H 2 O respectively. Significant different was shown in both groups before and after treatment, while no significant difference between the two groups. The scores of VAS were 6.194±1.731 and 3.968±1.335 respectively, showing significant difference.Abnormalities of nasal mucosa are common among OSAHS patients. It is practical to lower the CPAP pressure by improving the nasal ventilation conditions, thus the compliance of CPAP can be improved. Several papers with the same point of view have been published in recent years. Our study showed no significant difference on the improvement of nasal ventilation and the change of CPAP pressures between the two groups. Both Herba Schizonepetae and nasal steroid for continuous two weeks can lower the therapeutic pressure with no significant difference. However, the cost of Herba Schizonepetae is only one-fifth of the nasal steroid. Therefore Herba Schizonepetae is practical and cost-effective for people who are comfortable with herbal medicine, which is popular in China.We appreciate the participation of all subjects and the efforts of all the staff involved in the research.