BACKGROUND Price's social competition hypothesis interprets the depressive state as an unconscious, involuntary losing strategy, which enables individuals to yield and accept defeat in competitive situations. AIMS We investigated whether patients who suffer from major depressive disorder (MDD) would avoid competition more often than either patients suffering from borderline personality disorder (BPD) or healthy controls. METHOD In a simple paper-folding task healthy participants and patiens with MDD and BPD were matched with two opponents, one with an unknown diagnosis and one who shared their clinical diagnosis, and they had to choose either a competitive or cooperative payment scheme for task completion. RESULTS When playing against an unknown opponent, but not the opponent with the same diagnosis, the patients with depression chose the competitive payment scheme statistically less often than healthy controls and patients diagnosed with BPD. CONCLUSION The competition avoidance against the unknown opponent is consistent with Price's social competition hypothesis. DECLARATION OF INTEREST G.H. received research support, consulting fees and speaker honoraria from Lundbeck, AstraZeneca, Servier, Eli Lilly, Roche and Novartis. COPYRIGHT AND USAGE © The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.