Lean management (LM) principles were first developed by a Japanese manufacturing company to maximise value and minimise waste in the automotive industry. However, these principles can also be applied in the healthcare sector. This study aimed to illustrate the process of implementing LM principles in a radiation oncology department to streamline workflow and identify and reduce waste.This study took place in the Department of Radiation Oncology, Royal Hospital, Muscat, Oman, in December 2016. A value stream map (VSM) was created for the chain of processes followed in the department. A waste analysis was conducted to determine which processes did not add value for the patient or healthcare provider.Based on the VSM analysis, only six out of 13 steps were found to be of value. Necessary and unnecessary non-value-adding activities were identified. Sources of waste included parking and registration. In addition, variabilities in workload were noted.Overall, LM principles improve workflow, reduce waste and enhance patient and staff satisfaction. In the current study, the application of LM principles helped to improve value in a radiation oncology department.