Objective In the United States and most European countries, cancer diagnoses are disclosed to patients. In China, however, the trend toward full disclosure has progressed slowly. The present study aimed to explore attitudes toward truth‐telling practice among physicians, patients, patients' family members, and the general population, and reasons for nondisclosure. Methods We administered a short survey to 212 physicians, 143 patients with cancer, 413 family members of patients with cancer, and 1415 members of the general population. A MANOVA was performed to examine group differences in attitudes toward cancer disclosure. In addition, we interviewed 20 oncologists. Interview data were analyzed using NVivo10. After the interview, we administered another short survey to 143 patients with cancer. Results Quantitative data indicated that physicians were the least, and patients the most, in favor of disclosure. Qualitative data among physicians and follow‐up surveys among cancer patients revealed 5 reasons for the concealment of cancer diagnoses by physicians, including lack of awareness of patients' right to knowledge, cultural influences, insufficient medical resources and training, families' financial concerns, and the need to protect doctors from violence. Conclusion There is a discrepancy between the needs of patients and those in medical practice. These results deepen our understanding regarding the reasons for oncologists' attitudes toward nondisclosure.