The purpose of this study was to review the literature on the causes, diagnosis and the treatment of xerostomia. Xerostomia is not a disease, but a subjective feeling of oral dryness. It is caused by many local and systemic factors. The most common causes are drugs, anomalies and diseases of the salivary glands, high doses of radiation, chemotherapy, systemic diseases, mental illness, ageing, etc. Xerostomia can be transient or permanent with consequences such as infections of the oral mucosa, cervical caries, gingivitis, periodontitis, and inflammation of the salivary glands, burning sensation, and changes in tastes. Patients have difficulty chewing, swallowing, speaking and have problems with wearing dentures. On the basis of anamnestic data and clinical features, the doctors need to identify the symptoms of xerostomia, conduct diagnostic procedures in the doctor's office such as dental mirror adhesion test and sialometry measurements. If the diagnostic procedures demonstrate a positive finding on xerostomia, the patient then is referred to further testing in order to discover the cause of xerostomia. The treatment is multidisciplinary and multimodal aimed at curing the primary illness. Using different therapeutic methods, the doctor seeks to alleviate the subjective symptoms and restore the compromised quality of life to the patient