The objective of this study is to evaluate the effectiveness of Synbiotic preparation containing 108 CFU of Lactobacillus spp., Bifidobacter spp., S.Thermophilus and Prebiotic: Fructooligosaccharide (commercial name: Protexin, London, UK) on constipation symptoms in young men suffering from functional constipation. 66 young men suffering from functional constipation were included (by screening population of young men) in a randomized clinical trial, of whom 60 (Intervention: 31, placebo: 29) completed study period. Functional constipation was defined by Rome 3 criteria. Patients with systemic disorders, fever, recent weight loss, LAP, anemia, Diabetes Mellitus, nervous system disorder, or history of gastrointestinal surgery were excluded.