Abstract: An analytical method for quantifying ammonia in sidestream cigarette smoke (SCS)was developed with continuous flow analysis. Ammonia in SCS was collected by a "fishtail" chimney, by passing through a Cambridge filter pad and an absorption bottle containing hydrochloric acid. The combined collection was subjected to washing and extraction before being analyzed by a continuous flow method. The results showed that: 1)The method had good linearity (with correlation coefficient of 0.999 9)and the limit of detection was 0.12 mg/cig. The relative standard deviation was 6.8% (n=5), and the recoveries ranged from 86.0% to 112.0%. 2)The method was simple, rapid, accurate, and suitable for determining the level of ammonia in SCS.