BackgroundrnA liver disease of unknown etiology which is characterized by epigastric pain, fever, jaundice, nasalrnbleeding, peripheral edema and abdominal swelling progressing to ascites with high morbidity andrnmortality reported among humans in six districts of the North-Western Zone of Tigray, Ethiopia sincernApril 2002- 2010. This surveillance data analysis and outbreak/epidemic investigation was thus, aimed atrndescribing the magnitude of unidentified liver disease by person, place and time for recommendingrnpossible preventive and control intervention strategies to the disease. rnMethods rnStudy is conducted in North-Western Zone, Tigray region, Ethiopia. A line list was collected and casernregister log books of the districts were reviewed. Case definition was set based on the symptoms andrnsigns of the disease to identify cases. Surveillance secondary data of all six districts of the Zone preparedrnin a line list was reviewed, entered and analyzed in Microsoft Excel.rnResultsrnA total of 736 cases and 247 deaths were reported from April 2002 to June 2010, with an attack rate ofrn0.1% and case fatality rate of 33.5%. The median age of cases was 18 years which ranged between 1 andrn81 years old. Age group of 5-14 accounted 32.7% (241/736). Sixty percent of total cases and 63% ofrndeaths were males. Out of a total of 124 kebeles in these six districts 39 (31%) reported cases ofrnunidentified liver disease to date. rnConclusion and RecommendationrnMajority of cases affected by the disease were in the age group of 5-14, and with a higher proportion ofrnmale cases. Further research has to be employed in the area. Documents on how well cases werernmanaged should be sought at all relevant health facilities to evaluate the the previous management ofrncases inorder to recommend better future case management approaches.