Tobacco smoking negatively affects the quality of saliva and affects many biological parameters including salivary α-amylase enzyme activity. Salivary α-amylase enzyme is essential for the catabolism of carbohydrates. Forty- five healthy male volunteers aged between 18 and 69 years (40.0 ± 15.0) were divided into two groups, namely, the control group (n = 21) and the cigarette smoker group (n = 24). The effect of smoking on salivary α-amylase enzyme activity depends on the number of smoked cigarettes per day and the type of cigarettes as well as the period for how long the person smoking tobacco cigarettes was investigated. Different methods were used to analyze the activity of salivary α-amylase enzyme including the dinitrosalicylic acid method (standard colorimetric method). The results showed a significant increase (P < 0.05) in salivary α-amylase activity in Libyan smokers compared to the non-smokers in the morning and night, also, the findings showed a significant decline in salivary α-amylase activity during the increasing smoking period. The activity of salivary α-amylase in the young age smokers group increases in morning and night compared to the non-smokers group. There is no change in the activity of salivary α-amylase in the middle and older adult groups in the morning and night compared to young smokers group. In conclusion, smoking for a long period time more than 20 cigarettes per day decreases the activity of salivary α-amylase in Libyan subjects.