The purpose of this research was to examine the medical students' personality with stress and developmental level. The study explored three overarching topics: How are medical students' personality types reflected in an enneagram? Are there any differences between subtypes of stress points? How are the students' developmental levels by gender, academic level, and enneatypes? The subjects were 414 medical students in three Korean medical schools. Enneagram Personality Types Inventory (Korean version) was used. These enneatypes were divided into four subtypes: centers of intelligence, hornevian triads, self-consciousness, and harmonic group. Enneatypes and stress points were analyzed statistically by frequency and percentage of enneatypes, chi-square test, and ANOVA. Distribution of enneatypes; type 9 was the most frequent class (n=136, 32.9%). Types 1, 3, 4, and 9 had more disintegrated students than other types (chi2=59.2, p=0.000). Subtype analysis; in body-centered type more students were disintegrated than integrated or mediocre (chi2=25.8, p=0.000). In behavior patterns, aggressive and passive types showed more disintegration (chi2=25.2, p=0.000), and in self-consciousness groups only inner order types showed integration (chi2=19.3, p=0.001). In harmonic group, positive outlook types contained the most disintegrated students (chi2=20.5, p=0.000). Majority of medical students were in disintegrated developmental status. A program should be developed for students to know their ego-identity plainly and overcome their disintegration, based on their enneatypes. Such a program will help students improve their ways of thinking or their behavior and become more secure.