The purpose of this study is to evaluate salivary flow rate,salivary pH, and cariogenic activity using unstimulatedsaliva of the head and neck cancer patients. Twenty threecancer patients (19 males, 4 females) who had undergonechemotherapy and radiation therapy and twenty four healthyvolunteers (14 males, 10 females) as a control were included. Salivary flow rate, salivary pH, and cariogenic activity usingunstimulated saliva were examined. Compared to saliva ofthe control group, salivary flow rate (p<0.001) and salivarypH (p<0.001) were significantly lower in head and neckcancer patients. The colony counts of Lactobacilli was higherin head and neck cancer patients (p<0.05) than in controlgroup. These salivary factors and cariogenic activity canincrease the prevalence of dental caries in head and neckcancer patients.