This study applied Derdiarian's theory to analyze the information needs of a woman who had been newly diagnosed with breast cancer. Data was collected from a field study, specifically 17 process recordings were conducted. The findings included the followings: (1) Information needs were created by insufficient information, insufficient self-control, and increasing uncertainty; (2) Medical related information was gathered from people (volunteers, patients, health care professionals and relatives) and media (brochure and newspaper): and (3) Information included information on medical issues, chemotherapy, and daily care. The information needs of patients change with the progress of the disease, and thus health care professionals should assess patient needs and provide information accordingly.