Background: Physical or psychological adversity in childhood is associated with a higher risk for depression in adulthood, and with persistent serotonergic abnormalities in humans and in animal models. We hypothesized that reported childhood abuse would be associated with lower brain serotonin transporter (5‐HTT) binding potential (BPP, proportional to the number of available transporters) in adults. We examined healthy volunteers and subjects with major depressive disorder, a sample enriched for childhood abuse.