A MASCC/ISOO Clinical Practice Statement (CPS) is aimed at generating a concise tool for clinicians that concentrates practical information needed for the management of oral complications of cancer patients. This CPS is focused on the clinical assessment of salivary gland hypofunction and xerostomia in cancer patients. This CPS was developed based on a critical evaluation of the literature followed by a structured discussion of a group of leading experts, members of the Oral Care Study Group of MASCC/ISOO. The information is presented in the form of succinct bullets and tables to generate a short manual about the best standard of care. The objective assessment of saliva secretion involves an extra- and intra-oral clinical examination while the subjective assessment involves eliciting information on the patient's complaint of xerostomia and its impact on daily functioning. This CPS summarizes the common investigator- and patient-reported instruments used in clinical practice for assessing salivary gland hypofunction and xerostomia in cancer patients. There is a range of tools to assess salivary gland function in patients undergoing cancer therapy, patients recovering from cancer therapy, or cancer survivors. Clinicians should ideally conduct both objective and subjective measurements to ensure a clear understanding about the status of the patients in order to provide the most appropriate treatment.