Background: Cigarette smoking is a worldwide social epidemic and it is one of the main causes of preventable death and disability. Gingivitis, periodontitis, pocket depth, attachment loss, alveolar bone loss, and tooth loss are some of oral pathologies commonly found in cigarette smokers. The aim of this study was to explore, for the first time among Nigerians, the interplay between components of cigarette smoke and salivary levels of immunoglobulin classes so as to provide oral immunological based reasons for oral diseases in cigarette smokers. Materials and Methods: In this case-control study, 5 mL of unstimulated saliva was collected in plain sample bottles from 24 active smokers who smoke at least 6 sticks of cigarette per day and 21 sex and age-matched non-smokers who were apparently healthy. The samples were spun and supernatant stored at -20°C until assayed. The immunoglobulin levels of the samples were estimated using enzyme-linked immunosorbent assay (ELISA). Student′s t-test (unpaired) was used to determine significant differences between the two groups. P values less than 0.05 was considered significant. Results: No significant differences were observed in the mean salivary levels of IgG, IgA, and IgE. Only IgM was significantly lower in smokers compared with non-smokers (P = 0.038). The proportion of smokers with detectable level of salivary IgE was lower compared with controls. Conclusion: Our study showed that there is decreased salivary IgM in smokers. This observation suggests that reduced salivary immunoglobulin level of IgM might be involved in the pathogenesis of oral diseases in cigarette smokers.