Gastrointestinal symptoms are very frequent in myotonic dystrophy but largely unrecognized. They can be the revealing factors of the disease. We report 2 cases of 10 and 17-year-old children with persistent encopresis starting at the age of 3 and 5 years in spite of laxative treatment. Neurological examination and anorectal manometry provided the diagnosis of myotonic dystrophy. Procainamide treatment was introduced and the digestive symptoms improved. Any child with encopresis should have complete evaluation to rule out the diagnosis of myotonic dystrophy and physicians should look for upper and/or lower gastrointestinal symptoms in every patient with myotonic dystrophy.