Objective: Previous study showed that salivary immunoglobulin A (IgA) level in the active smoker or dental caries were lowers than non-smoker or dental caries, but the salivary IgA in the passive smoker with or without dental caries is unknown. Methods: The aim of this study was to investigate the difference of salivary IgA on active smoker with caries, active smoker without caries, passive smoker with caries, and passive smoker without caries, on five subjects in each group. The salivary IgA was measured using radial immunodiffusion method. Results: The results showed that there were significant differences (p<0.01) between four groups. Multiple comparisons using Tukey HSD showed that salivary IgA level on active smoker with caries (16.78±1.75mg dL-1) was the lowest than the other. The salivary IgA on active smoker without caries (33.4±1.97mg dL-1) was lower than passive smoker with caries (39.80±2.18mg dL-1), and the last was lower than passive smoker without caries (60.70±4.31mg dL-1). Conclusions: It was concluded that the humoral immune response against dental caries on active smoker was very low.