Tobacco smoking is affecting fundamental aspects of human health. This preliminary study was set to investigate the effect of tobacco smoking on the salivary pH. The saliva is an essential part of healthy oral cavity, it is mostly made of water and also contains other substances that your body needs to digest food and keep your teeth strong. Smoking is expected to have an effect on salivary pH. The salivary pH levels were measured using digital pH meter in 100 voluntary participants in Baghdad- Iraq. The participants were divided into two groups of 50 subjects in each group: smokers and non-smokers. Along with that, the reasons behind tobacco smoking also were investigated in a separate group of 82 smokers using a prepared questioner for this purpose. The results showed decrease salivary pH average levels in the tobacco smokers compare to the non-smoker group (7.058 and 7.168 respectively), however, these differences did not reach the significant level. Regarding the investigation of the reasons behind tobacco smoking habit, seeking for fun, overcome psychiatric problem, anger, friendship, relieves stress and anxiety and work problems (((29 (35.4%), (28(34.1%), 27(32.9%), 22(26.8%), 22(26.8%), 21(25.6%) respectively, were on the top of the listed reasons for smoking tobacco cigarettes stated by the questioned participants. Participants who think that cigarettes could help to relieve boredom (age average 35.3 yrs (17-55 yrs) smoke the largest number of cigarettes (30(20-60) compare to those who smoke for other reasons.