Diarrhea is a common, often dose-limiting toxicity associated with cancer chemotherapy treatment. However, the problem is not well recognized and frequently is not managed appropriately. The primary objectives of the current study were to describe the sociodemographic and clinical characteristics of cancer patients with chemotherapy-induced diarrhea (CID) and describe the clinical consequences of CID on treatment changes. This was a retrospective review of medical records from 378 cancer patients who experienced diarrhea while receiving chemotherapy at 25 geographically dispersed US cancer clinics. Severe diarrhea (National Cancer Institute-Common Toxicity Criteria grades 3 or 4) was experienced by about one third of patients during their chemotherapy. Patients who experienced CID underwent changes in their chemotherapy treatment, including dose reductions (45%), delays in therapy (71%), reduction in dose intensity (64%), and discontinuation of therapy (3%). Dose reductions were statistically significant. Although the majority of diarrhea was grade 1, almost one half of all patients required dosing reductions, and more than one half of these patients experienced dosing delays. Changes to chemotherapy treatment resulting from CID may ultimately impact patient clinical outcomes.