This study investigated the relation between defense mechanisms and Dark Triad traits using a cross-sectional correlational design with a sample (N = 307) recruited online using the Prolific platform. We hypothesized that immature defense mechanisms would positively correlate with the so-called Dark Triad traits of narcissism, psychopathy, and Machiavellianism. We found this hypothesis supported for psychopathy and Machiavellianism, but not narcissism. Instead, we found that mature defense mechanisms were positively correlated with narcissism. Our findings partly replicate previous research on this topic by Jonason and colleagues and Richardson and Boag.