With improvements in cancer survival rates, more patients with cancer are living longer, and hence, cancer is becoming viewed as a chronic illness requiring long-term management. An important aspect of patient care during and after cancer treatment is patient health behaviors. For example, sequelae from various cancer treatments, such as chemotherapy and radiotherapy (RT), can compromise health in a variety ways, including decreased immune functioning, cardiotoxic effects of chemotherapy and/or RT, and weight gain. In addition, the stress caused by a cancer diagnosis and its treatment can disrupt existing health behaviors or exacerbate unhealthy behaviors. Continued smoking or alcohol use can complicate treatment and increase risk for further malignancy. Furthermore, decreased physical activity and poor nutrition can cause weight gain, which may contribute to secondary health problems such as cardiovascular disease and diabetes. The authors reviewed the extant literature on four key health behaviors among patients with cancer and survivors: healthy diet, reduced tobacco use, reduced alcohol use, and increased physical activity. They described the prevalence of these behaviors, reviewed the effects of interventions designed to alter unhealthy behaviors, and discussed the implications and future directions for this emerging area of research. Cancer 2005. © 2005 American Cancer Society.