We describe the vicissitudes of depressed mood for one medical school class that was assessed repeatedly over time, from the first day of medical school until several months short of graduation, using the Beck Depression Inventory (BDI). Using an arbitrarily defined BDI cutoff point of 14 or greater, at least 12% of the class showed considerable depressive symptoms at any assessment during the first three years; the largest fraction (25%) was symptomatic near the end of the second year. The median class BDI score increased almost threefold during the first two years. Students were likely to be in a similar class ranking at all assessments, indicating that for many students dysphoric mood was enduring. Those with BDI scores of 21 or greater were more likely to quit medical school. Students with high scores for dysphoria were not more likely to evidence a family history of major depression or concomitant substance abuse. Women medical students were not more vulnerable to depressed mood than men.