Objective: Severe anaemia and severe eosinophilia are commonly reported to occur in hookworm infection. But chronic diarrhea is not commonly reported to occur in hookworm infection. Hence a detailed study was done to know about the occurrence of chronic diarrhea in addition to severe anaemia and severe eosinophilia in patients having hookworms while doing upper gastro-intestinal endoscopy in our institute. Methods: A study of 1259 patients who had undergone upper gastro-intestinal endoscopy in our institute for a period of 5 years from May 2009 to April 2014 was carried out in order to find out the occurrence of chronic diarrhea in addition to severe anaemia and severe eosinophilia in patients having hookworms in duodenum while doing upper gastro-intestinal endoscopy. Results: Of these 1259 patients, as many as 18 patients were found to have hookworms in duodenum while doing upper gastrointestinal endoscopy. Of these 18 patients, 4 patients were lost for follow up and full details about their investigations were not available. Among the remaining 14 patients, one patient was found to have severe anaemia but without chronic diarrhea. Three patients were found to have severe eosinophilia or hypereosinophilia [absolute eosinophil count or aec more than 1000 cells/ cu.mm] but without chronic diarrhea. But interesetingly, one patient was found to have severe anaemia and severe eosinophilia [absolute eosinophil count or aec -1100 cells/cu.mm]along with chronic diarrhea . Hence full details about this patient with chronic diarrhea in addition to severe anaemia and eosinophilia is thoroughly analysed and discussed in detail in this article. Conclusion: Severe anaemia and eosinophilia are commonly reported to occur in hookworm infection. But chronic diarrhea also occurs rarely in hookworm infection. It is a well known fact that hookworm infection should be suspected strongly in patients with significant anaemia and eosinophilia. But hookworm infection should also be suspected in patients with chronic diarrhea, especially in tropical and subtropical countries.