Themain purpose of the current study was to investigate the effect of mind mapping strategy on developing 46 randomly selected EFL preparatory stage  students' writing skills from Rabaa El Adawia Preparatory School, Kafr Saqr Educational Directorate, Sharkia Governorate in the second semester of the academic year 2019-2020. The researcher adopted quasi experimental design. The participants of the study were equally divided into the experimental and control groups. To achieve the purpose of the study, the researcher designed an EFL writing skills questionnaire, an EFL writing pre-posttest, and a rubric. The experimental group was taught by the use of mind mapping strategy while the control group received regular instruction. The results of the statistical analysis indicated that the experimental group writing skills developed as a result of utilizing mind mapping strategy. So, the researcher recommended that mind mapping activities should be integrated within the learning curriculum. It is suggested that further studies should investigate the relationship between mind mapping strategy and other writing skills, i.e. critical and creative writing at various educational stages.