Background: The present study aims to determine the prevalence of nursing missed care and associated factors at the oncology departments in Gaza Strip, Palestine. Method: This cross sectional study was conducted among all nurses who worked at the only two hospitals offer oncology nursing care in Gaza Strip, Palestine between May to July 2020 using a self-administered questionnaire. Results: Data from 52 nurses (44 had bachelor and 8 had diploma certificate) on five oncology departments in the European Gaza and Al-Rantisi hospitals revealed that the overall prevalence of missed nursing care was 39%. The most common areas of missed care reported were; providing oral hygiene for those who need (n=39, 75%), treatments and some of nursing procedures left undone because of lack of time (n=34, 65.3%), and always nurses consider cleaning of patient’s room or equipment (n=30, 57.7%). The main factors leading to missed nursing care were lack of enough nurses, no opportunity for nurses to participate in policy decisions, absent of active quality assurance program, management do not listen and response to employee concerns, and there is no a preceptor program for newly hired nurses (weighted means: 37.8%, 37.4%, 36.8%, 36%, and 35%, respectively). Conclusion: The findings of the present study demonstrated the need for more quality improvement efforts to reduce missed nursing care in the oncology departments. Considering issues such as shortage in staff number, nurses’ continuing education/training programs and involvement in policy decisions, and direct response to the career concerns could reduce the prevalence of missed care.