Cancer is a serious health issue in Iraq, where it is the second largest causes of death, according to Ministry of Health data from 2016. Cancer is among the primary causes of mortality and morbidity, In 2018, 9.6 million people died, or one per six death. Lung, colorectal, stomach, prostate, and cancer of liver affect males, whereas cervical, colorectal, breast, lung, and thyroid cancer affect women . To assess the Nurses Knowledge toward nutritional instructions need for patients with Cancer at oncology center in AL-Diwaniyah. Governorate. And To Find out the Association Between Certain demographical data and Participation in Training Course with Oncology Nurses' Knowledge. A quasi experimental study design is conducted at Al-Diwaniyah Specialized Oncology Center, from 17th March 2021 to 15th May 2022. For the aim of the study, the researcher created the program and instrument. A non-probability purposive sampling had been consisted of (60) oncologic nurses have been chosen to obtained represent and accurate data. The sample size is (60) nurses, split into two groups, one of which includes of (30) nurses as the study group and the other of which consists of (30) nurses as the control groups. The study groups taking the educational programs that deals with nutrition of oncologic cancer patients, the control group, on the other hand, has not been subjected to the instructional programs. To obtain data from study participant, the researcher built the tools consisted of two parts: First part is the socio-demographic variables and second part the knowledge of the nurses (knowledge related to nutrition of oncologic patients The study instrument's validity was verified by presenting it to (19) experts, and its reliability was assessed using the internal consistency approach. To determine the difference between the study and the control groups, descriptive analysis and analytical inferential analysis were performed. The study's result revealed that there is very significant difference in between study group's (pretest and posttests) in terms of (nurse's knowledge of nutrition of oncologic patient people with cancer), (MEAN ± SD= 2.37±0.451) comparing to the pretest score (MEAN ± SD=1.58±0.402) due to effectiveness of an educational programs. The study finds that an education program focusing on food for oncologic patient cancer patient has a high chance of success of treatment. To establish nutritionist nursing specialty in our country similar to other developed countries to maintain our community health. Establishing one year diploma post graduate nursing studies for academic nurses in our nursing colleges to strengthen the nursing profession in these field. And specialized training sessions for nurses with exams to gain advantage and have an influence on the knowledge of oncology nurses, and oncology nurses must have particular pre-oncology educational courses before participating in the cancer ward.