OBJECTIVES: Validation of health outcomes research of cancer becomes critical for the quality assessment of outcomes research. In Principles of Good Practice for Decision Analytic Modeling published by ISPOR Task Force ISPOR Task Force in 2003, validation was suggested: internal validation, between-model validation, and external & predictive validation. Also, Health Technology Assessment NHS R&D HTA Programme published Review of guidelines for good practice in decision-analytic modelling in health technology assessment in 2004, suggesting a checklist of Dimension of quality: Structure, Data, and Consistency (internal and external). The objective of this research is to review and summarize validation activities in cancer outcomes researches published between 1998 and 2009. Secondary objective is to identify any changes in validation activities post regulatory guidelines. METHODS: The relevant articles are searched by using PubMed.gov with key words of Validation Health Economics Cancer. Frequencies are tabulated by validation criterion and publication year. Statistical methods employed for testing each validation criteria are summarized. RESULTS: Sixty-seven articles are found. 31 articles reveal validation effort. Criteria frequently tested for validation are external validity, internal validity, face validity, criterion validity, content validity, predictive, reliability, responsiveness, sensitivity. Sixty-eight percent of articles were published since 2003 and 89% since 2000. For testing validity of research model, correlation, regression, mean are statistics employed frequently. For testing validity of data, sensitivity & specificity, and positive predictive value are statistics used. CONCLUSIONS: Validation effort may have increased since 2003 when guidelines from regulatory agencies have been published. But most articles' validations were partially done. Few articles followed the guidelines to the full extent. In contrast to validation of quality of life instruments, validation of health economics outcomes models lacks theoretical foundation. It is recommended to follow guidelines to enhance credibility of the health outcomes research.