Cancer is the leading cause of death in Taiwan. Cancer patients often suffer from severe pain that limites the quality of life through provoking feelings of helpless, uneasiness, anxiety, depression, anger, fatigue, and sleep disturbance. The purpose of this study was to explore patients' pain, anxiety, depression, and sleep disturbance affer their first course of radiotherapy and related factors. The study was designed as a correlational study with seventy subjects from a medical center in Taiwan. This study used instruments, such as the VAS pain scale, the short form McGill Pain Questionnaire, the State-Trait Anxiety Inventory, the Beck Depression Scale, the RW Questionnaire, and VSH Sleep Scale Data analysis was conducted using Descriptive analysis, Fisher's exact test, t-test, one-way ANOVA, Pearson's correlation coefficient, and non-parametric test. The findings were as follows: Patients who were sampled in this study had nasopharyngeal carcinoma (NPC), prostate cancer, breast cancer, lung cancer, and uterine cervix cancer in sequence. Duing the first course of radiotherapy, fifty two percent of the patients had suffered from mild pain, but breast cancer and lung cancer patients suffered from a more severe pain. The anxiety level was either moderate or severe for all subjects. Patients with NPC had the most severe anxiety level compared to others. Patients under fifty years of age had more anxiety problems than patients with an age of fifty on older. The depression level for all subjects were mild, except for lung cancer patients who had suffered form moderate depression. The relax state and sleep situation of the patients proued fair with no difference ofter diagnosis. Pain in cancer patients was related to trait anxiety and depression. State anxiety and depression were related to relation and sleeing situation. These important findings could be a reference for further interventions for cancer patients.