Introduction: Functional Gastrointestinal Disorders (FGIDs) are a frequent motive for health care need during infancy and adolescence thus causing serious problems socially and in family dynamics. Objective: To know the frequency of FGIDs and to identify and validate its clinical characteristics according to Roma II criteria. Methods: Within a 2 year period 227 consecutive patients less than 17 years of age diagnosed as having a functional disorder were given a questionnaire for symptoms to be filled out by them and/or parents or tutors and were subject of a complete physical examination in their first visit. These data was loaded into an Epinfo-6 Program. Percentual distribution was the selected statistic method. Results: Cyclic vomiting syndrome 19 (8,4%), 2-10 years, mean 5. Female 57,9 %, Migraine 6 (31,5%), Irritable bowel syndrome as accompanying disease 2 (10,5%). Abdominal pain 90 (39,6%), 5-16 years, mean 10: Functional dyspepsia 31 (34,5%,) 6,5-16 years, mean 12. Male 64,5%. Irritable bowel syndrome 32 (35,6%, 5-15 years, mean 9,5. Female 53,2%. Functional abdominal pain 17 (18,8%, 5-14 years, mean 8. Female 76,5%. Abdominal migraine 9 (10%), 6,5-11 years, mean 8,5. Female 55,6%. Aerophagia 1 (1,1%), 15 years, male. Functional diarrhea 44 (19,4%), (6-36 months, mean 17). From these (44,7%) 6-12 months. 59,1% Male. 43,1% started after an acute diarrhea episode. Undernurished 11,4%. History of Giardia 18,8%. Disorders of defecation 74 (32,6%): Infant dyschezia 5 (6,8%), (15-30 days, mean 22). Male 60%. Functional Constipation 21(28,4%), 2-5 years, mean 3,5. Female 52,4%. Functional fecal retention 45 (60,8%), 1,5-12, mean 5,5. Male 60%. Non-retentive fecal soiling 3 (4%), 9-13,5 years, mean 12. Male 100%. Conclusions: FGIDs are frequent in our children and adolescents. Diagnosis based in clinical symptoms according to Roma II criteria showed to be useful for them as a diagnosis method and for their following, though age restrictions are an inconvenience specially in defecation disorders.