Abstract Background Patient awareness plays an important role in integrating palliative care into the patient care process. Lack of awareness can create a negative attitude towards palliative care and affect patients' decisions during the treatment process. The present study was conducted to determine the level of knowledge about palliative care in Iranian patients with cancer. Methods The descriptive study was conducted with a convenience sample of 103 cancer patients admitted to an oncology center in Yazd, Iran, A three-part questionnaire including demographic information, sources of palliative care information and the Palliative Care Knowledge Scale (PaCKS) was used to collect data. All statistical analyses were performed using software SPSS 21. Results The mean age of patients was 36.2 ± 13.5 years. Of the total, 38.8% of patients received information about palliative care through the media and 36.9% from the treatment team. On a scale of 0 to 13, the mean PaCKS score was 6.7 ± 3.7. A ‘good’ level of knowledge was reported by 29.1% of participants; however 84.5% stated that they should leave other doctors at the time of receiving palliative care, 71.8% considered palliative care for patients in the last six months of life, 84.5% considered palliative care for patients with cancer, and 70.9% stated that palliative care encourages people to discontinue treatments aimed at treating their disease. Conclusion Our study found most cancer patients have a moderate to weak level of knowledge and considerable misinformation about palliative care, which highlights the importance of providing palliative care education. The development of training programs in this area could play an effective role in improving patients' knowledge of palliative care.