Xerostomia or dry mouth sensation is considered a complex condition that affects several stomatological functions that drives to the detriment of the quality of life of individuals who suffer from it. Often, xerostomia is accompanied by a decrease in salivary flow or hyposalivation, and this condition leads to oral health problems such as dental caries, candidiasis, and mucosal complications. Currently, the diagnosis and therapeutic methods for this condition are varied and it is difficult to achieve favorable results in all cases, since the etiology seems to be multifactorial where both local factors and systemic conditions would participate. This chapter presents, in a concise shape, the relevant data about etiology of xerostomia, such as age, autoimmune diseases, systemic diseases, infectious diseases, neuropathic complications, psychogenic factors and therapeutically consumption of drugs among others, and the current available treatments.