Giardia lamblia is a cosmopolitan parasite with a worldwide distributionand the most common protozoan isolated from the gastrointestinal tract. Themost common symptoms of giardiasis are diarrhea, abdominal pain, bloating,flatulence and weight loss resulting from malabsorption. These symptomsmay overlap with those of patients with other gastrointestinal disorders.Classically, diagnosis of giardiasis is performed by microscopic examinationof stool samples and/or duodenal biopsies or aspiration. Further new methodsincluding immunocromathography and immunofluorescence on stoolsamples. The aim of the present study is to evaluate the prevalence of Giardialamblia infection in irritable bowel syndrome patients, to study the possibleassociation between them, to evaluate the recommended nutritivesupplements in conjunction to the conventional therapeutic measures intreatment of patients and to follow up those patients with a regularly plannedassessment. The obtained results from the present study concluded that among160 irritable bowel syndrome patients, Giardia lamblia was found in 45individuals (28.13%). Highest improvement was achieved by a combinationtherapy between tinidazole, probiotics and wheat germ oil capsules.