The aim of this study was to explore the longitudinal development of the key self-regulated learning (SRL) processes in medical students with low-academic performance during a combined SRL diary intervention. Second-year medical students with low-academic performance completed a weekly online combined SRL diary intervention (explicit SRL instruction with structured SRL diary) during a basic sciences nervous system block (NSB). Longitudinal development of the students' key SRL processes of planning and self-reflection was identified with analysis of the diary responses using framework analysis. Qualitative data were analyzed from 80 dairies completed by 20 students. The most frequent planning process was goal setting for studying the material, especially in preparation for their NSB examination. The most frequently stated study strategies that developed longitudinally were reviewing the material and managing their time for study and the volume of content. During self-reflection, students frequently attributed their success in NSB learning to the SRL intervention, especially their development in using the strategies of elaboration, reviewing the material, and managing both study time and the volume of content. Participants using the combined SRL diary developed an adaptive approach toward enhancing their strengths and eliminating their weaknesses in their use of key SRL processes while studying for the NSB block examination. Combined SRL diary interventions appear to have potential in supporting students with low-academic performance to improve their performance in basic sciences, including anatomy education. Further research is recommended with larger numbers of students and across other topics.