This study investigates the process from suicidal thoughts to suicidal planning among physicians. First, predictors at medical school of postgraduate suicidal planning are identified. Then, the transition from suicidal thoughts to planning over three to four years is explored. Common predictors for both postgraduate suicidal planning and transition from thoughts to planning were depressive symptoms and personality traits. Reality weakness was the most decisive trait for aggravation in suicidal ideation, and this personality trait needs further study in suicidal research and clinical awareness.