Cancer treatment-induced diarrhea affects a high percentage of patients with cancer that receive chemotherapy or radiation treatment. Widely used criteria for measuring treatment-induced diarrhea, such as the National Cancer Institute Common Toxicity Criteria, do not account for important characteristics of treatment-induced diarrhea. These characteristics include the assessment of the duration of the diarrhea, coexisting symptoms, abdominal cramping, or the presence of nocturnal diarrhea. Until recently, there were no universally accepted guidelines for the management of diarrhea. An expert panel developed guidelines with recommendations regarding assessment of the patient and treatment. These guidelines stress the importance of a thorough assessment of the patient, and treatment based upon severity of symptoms. By employing these guidelines, the aggressive management of diarrhea may impact the overall morbidity of this symptom. Education regarding the importance of diarrhea is essential. Patients who are informed will better understand their role in managing this side effect and when to contact their health care provider with emergent symptoms. Early recognition and management of diarrhea will be essential to improve control of diarrhea, and in turn will positively impact patients' quality of life.