Patients undergoing cancer treatment experience a multitude of symptoms that can influence their ability to complete treatment as well as their quality of life during and after treatment. This cross-sectional study sought to describe the dietary changes experienced by cancer patients and to identify associations between these changes and common treatment symptoms. A convenience sample of 1199 cancer patients aged 18 yr and older undergoing active treatment were recruited from 7 cancer centers to complete a self-administered paper-and-pencil survey. Descriptive analyses were conducted to estimate prevalence of dietary changes and chi-squared tests were used to examine associations between dietary changes and health outcomes. Approximately 40% of patients reported a decreased appetite since beginning treatment, and 67.2% of patients reported at least 1 chemosensory alteration. Increased taste sensitivities were more common than decreased taste sensitivities, with increased sensitivity to metallic being the most common taste sensitivity (18.6%). Patients also had increased sensitivities to certain smells including cleaning solutions (23.4%), perfume (22.4%), and food cooking (11.4%). Patients reported a wide range of food preferences and aversions. Patients who had less energy or lost weight since beginning treatment were more likely than others to report treatment-related dietary changes.