Diagnostic confirmation of fatal Yellow Fever (YF) is essential for epidemiological surveillance in YF endemic regions. An immnunohistochemical method for Yellow Fever antigen detection in sections from formalin-fixed and paraffinembedded liver tissues was evaluated. Sensitivity of procedure was 98.30%, it was determined in 59 cases with YF clinico-pathological and epidemiological criteria, that ocurred in Colombia from 1934 until1992 including typical, atypical and late YF cases: 58 cases were positive while 1 case with severe autolytic changes was negative. On the other hand, none of 10 cases with histopathological diagnosis different from YF, including 4 cases with fulminant hepatitis originated by hepatitis B and delta virus coinfection, showed immnoreactivity (specificity was 100%). The results suggest that this immunohistochemical method could be a useful tool for the accurate diagnosis of YF difficult cases in reference laboratories.