Beta–thalassemia minor is a symptomless carrier state of a hemoglobinopathy which predisposes to bacterial infections. We report three cases presenting with giardiasis, a parasitic infection of gastrointestinal tract caused by Giardia lamblia. Patients presented with recurrent diarrhea and abdominal pain for over a year. An esophagogastroduodenoscopy finding varied from normal to acute duodenitis. Duodenal biopsy demonstrated changes consistent with mild chronic non-specific inflammation with G. lamblia trophozoites. All three patients were diagnosed as β -thalassemia minor hemoglobin electrophoresis. They were treated with Diloxanide furoate 500 mg and Metronidazole 400mg three times daily for five days. Their symptoms resolved and a stool test repeated one week after the end of treatment was normal. The host immune system both humoral and cellular components have a role in protection and clearance of Giardiasis. However, β -thalassemia minor patients have an observed probability of gardiasis but not a confirmed incidence.