Administration of oral of morphine for pain management to adult cancer patients has remained a great challenge. Nurses working in medical wards of Kenyatta National hospital have been faced with challenges of inadequate knowledge and attitudes of oral morphine administration to adult cancer patients. Oral morphine would provide relieve of pain in adult patients suffering from moderate or severe pain resulting from cancer. The main objective of the study was to establish nurses’ knowledge, and attitudes on administration of oral morphine for pain management to adult cancer patient in medical wards, Kenyatta National Hospital. A descriptive study was carried out and a total of 34 nurses participated in the study. Data was collected using structured, open-ended questionnaires for respondents. Data was analysed using the Scientific Package for Social Sciences (SPSS) software version twenty-one. Majority of the respondents 71.2% (n=24) received training on administration of oral morphine through on job training, (48.1%) respondents were undecided on administering oral morphine. Majority at (76.9%) nurses underestimated patients’ pain and all nurses agreed their reluctant to administer oral morphine because of respiratory depression. The study concludes that adult cancer patients with pain are not adequately relieved of pain and majority of nurses have inadequate knowledge and attitudes on administration of oral morphine. This study recommends continuing education programs on administration of oral morphine to adult cancer patient for nurses to facilitate acquisition of skills of oral morphine administration to relieve pain to adult cancer patients.