Introduction: Pneumonia is inflammation of lung parenchyma caused by virus, bacteria, fungus and parasite. Treatment efficiency at hospital can be evaluate by clinical pathway, that is evidence based tool for guiding health that is established internationally since 1980’s. Copeptin biomarker measurement can be used as tool for CAP clinical pathway evaluation. This study objective is to find out that implementation copeptin biomarker on clinical pathway of CAP. Methods: A mixture of correlative quantitative design between levels of copetine, length of stay and action research. Taking samples of pneumonia patients who were examined for copeptin levels in 2018 from medical record followed by the action research method. Results:It was obtained 25 CAP patients examined copeptin levels were then associated with length of stay which found a positive and significant relationship with length of stay with the strength of strong category relationships ( r=0,600; p =0,001). These results are used for evaluating clinical pathways by proposing that each pneumonia patient be admitted to inpatient care for copeptin levels and the results used to estimate treatment duration. The evaluation carried out 2 cycles of action research. The results of the action research that the levels of copeptin can be used for clinical pathway evaluations in research but cannot be routinely examined given the expensive examination. There is an improvement in the implementation of clinical pathway in Moewardi hospital that only medical who initially evaluated clinical pathway. Within this research, we was conducted training, creation and implementation of clinical pathways by involving other care professionals such as nurses, nutritionist and pharmacist. Conclusion: Correlation copeptin biomarker with length of stay CAP patient and the copeptin biomarker on clinical pathway community acquired pneumonia can not implementation excause expensive but there is an improvement in the implementation of clinical pathway evaluation at Moewardi hospital.