Inclusion Criteria:

1. Male or female constipated outpatients between the ages of 4 and 16
2. Currently taking a dose of less than or equal to 17g of PEG 3350 powder that has been consistent for at least 4 weeks
3. Current treatment is considered successful – defined as greater than 2 bowel movements per week with no accidents
4. Are otherwise in good health, as judged by a physical examination
5. If female and of childbearing potential, patient must be using oral contraceptives, depot contraceptives, intrauterine device, or testifies that she is monogamous with a vasectomized partner, or practices abstinence and will continue to do so during the duration of study
6. In the investigator’s judgment, patient or guardian is mentally competent to sign an instrument of informed consent

Exclusion Criteria:

1. Patients with heme positive stool at baseline exam
2. Patients who are impacted at baseline exam
3. Patients that are not receiving PEG 3350
4. Patients on PEG 3350 that continue to have problems
5. Patients with known or suspected perforation or obstruction
6. Patients with a history of gastric retention, inflammatory bowel disease, bowel resection, or colostomy
7. Patients with a known history of organic cause for their constipation.
8. Patients currently using medications known to cause constipation. These include Opiates, antidepressants, SSRI’s, antimotility agents and anticholinergics.
9. Patients who are breastfeeding, pregnant, or intend to become pregnant during the study
10. Female patients of childbearing potential who refuse a pregnancy test
11. Patients who, in the opinion of the investigator, should not be included in the study for any reason, including inability to follow study procedure
12. Patients with known allergy to PEG or PEG containing medications
13. Patients who, within the past 30 days have participated in an investigational clinical study