The incidence of hematologic malignancy increases with age; thus, the number of older patients who require intensive chemotherapy is expected to increase with the aging population. In Korea, 61.8%, 59.3%, 47.0%, and 46.7% of newly diagnosed cases of multiple myeloma, myelodysplastic syndrome, myeloproliferative disorder, and non-Hodgkin lymphoma, respectively, occurred in patients aged >65 years in 2018. Health status among older patients, defined by frailty, age-related syndrome of physiological decline and increased vulnerability, is associated with adverse health outcomes. Health status is highly heterogeneous among older patients, and treatment outcomes vary according to frailty and physiologic age rather than chronologic age. Comprehensive geriatric assessment (CGA) is a multidimensional and multidisciplinary diagnostic and treatment process that identifies multiple domains, including functional status, cognition, comorbidities, medications, socioeconomic status, and nutritional status, to develop a coordinated plan to improve treatment-related outcomes and quality of life. Frailty can be assessed with CGA findings, and CGA is considered the “gold standard of care” for frail, older patients. Through CGA, unidentified problems can be assessed, and pre-emptive and non-oncologic interventions can be delivered. CGA is an objective and reliable tool for predicting further treatment-related complications and identifying patients for whom intensive chemotherapy with curative intent is appropriate. CGA should be considered a routine practice before starting treatment planning in older patients diagnosed with hematologic malignancies who require intensive chemotherapy. Further study is needed to allocate individualized treatment plans or multidisciplinary geriatric interventions according to CGA results.