Purpose: A theory of blood-CSF barrier has been postulated for interpretations of clinical diseases. The microenvironment is enriched in specific molecules following physiological rhythms. In this study, we examined the possible role of CSF transthyretin in the patients who required shunt dependences after episodes of aneurysmal subarachnoid hemorrhage (aSAH).Materials and Methods: Over a 5-year period (2004-2009), there were 147 patients (79 females and 68 males) with a mean age of 58.2 years (range from 43 to 79 years) suffered from subarachnoid hemorrhage. 81 of them (subcategorized by traumatic, aneurysmal and idiopathic groups) developed altered CSF hypodynamic state contributing to the chronic hydrocephalus. The CSF samples were collected during their first shunt surgeries. The transthyretin was quantified to validate its clinical relevance to shunt dependence.Results: The transthyretin levels in three-group patients were statistically compared. The simple linear regression analysis was applied to our proposed correlation. The Pearson correlations coefficient revealed a significantly positive result (R^2=0.72 in traumatic group and R^2=0.86 in aneurismal group). There is significantly statistical meaning for tramatic and aneurysmal patients with regard to tracing CSF transthyretin to predict the intent-to-treated hydrocephalus secondary to aSAH (Both p-value≦0.05).Conclusions: In our study, the CSF transthyretin could be a important CSF maker to correlate the clinical shunt-dependence. As specific for aneurysmal cases, a prospective randomized study is further required to verify its reliability rather than traumatic and idiopathic occasions.