Abstract A preliminary account is given of a controlled personality investigation of 116 male lung cancer patients and 123 male non-cancer controls, in respect of extraversion and neuroticism, using the short form of the Maudsley Personality Inventory. The study was undertaken as one test of a hypothesis that lung cancer patients had a significantly diminished outlet for emotional discharge as compared with non-cancer patients. Account was taken of the presence or absence of a history of psychosomatic disorders in both lung cancer patients and non-cancer controls. The main findings, which are tentative, are that lung cancer patients are somewhat extraverted and markedly lower in neuroticism compared with non-cancer controls, and that there may be interaction effects with psychosomatic disorders. The available evidence suggests that lung cancer patients have personality features distinct from (1) the general cigarette smoking population, (2) non-cancer patients with a history of commonly accepted psychosomatic disorders, and possibly (3) patients with cancer in other sites.