Abstract: Cancer pain is an inherently subjective feeling. As such, a patient's report of pain is the basis of assessment. Self-reported questionnaires are extensively used in clinical practice and research. Single-item unidimensional rating scales are often used to assess pain intensity. Numerical rating scale is recommended by the European Palliative Care Research Collaborative. Multidimensional measurements, such as brief pain inventory and short-form McGill pain questionnaire (revised version), can also be used for more comprehensive pain assessments than other questionnaires. Furthermore, specific tools can be applied when cancer-related breakthrough pain or neuropathic pain is assessed. For patients with cognitive function impairments, face rating scale is a useful tool to screen pain. Multidimensional measurements should also be used for further evaluation. In cancer pain evaluation, the development of simple and practical computer-administered questionnaires is a new trend. Repeated cancer pain assessment is strongly recommended regardless of the applied scale.