Background:Prior studies have shown a marked drop in empathy among students during their third (clinical) year of medical school. Curricula developed to address this problem have varied greatly in content and have not always been subjected to validated measures of impact. Methods:In 2015, we initiated a Human Kindness (HK) curriculum for the initial 2 years of medical school. This mandatory 12-h curriculum (6 h/year) included an innovative series of lectures and patient interactions with regard to compassion and empathy in the clinical setting. Both quantitative (Jefferson Scale of Empathy [JSE]) and qualitative data were collected prospectively to evaluate the impact of the HK curriculum. Results:In the initial Pilot Year, neither 1st (Group 1) nor 2nd (Group 2) year medical students showed pre-post changes in JSE scores. Substantial changes were made to the curriculum based on faculty and student evaluations. In the following Implementation Year, both the new 1st (Group 3) and the now 2nd year (Group 4) students, who previously experienced the Pilot Year, showed significant improvements in post-course JSE scores; this improvement remained valid across subanalyses of gender, age, and student career focus (e.g., internal medicine, surgery, etc.). Despite the disappointingly flat initial Pilot Year JSE scores, the 3rd year students (Group 2) who experienced only the Pilot Year of the curriculum (i.e., 2nd year students at the time of the Pilot Year) had subsequent JSE scores that did not show the typical decline associated with the clinical years. Students generally evaluated the HK curriculum positively and rated it as being important to their medical education and development as a physician. Discussion:A required preclinical curriculum focused on HK resulted in significant improvements in medical student empathy; this improvement was maintained during the 1st clinical year of training.