Lacombe describes the successful analysis of a forty-one-year-old male identical twin affected by a severe obsessional neurosis with a masochistic compulsion to cheat. His childhood relation to his twin was marked by intense preoedipal ambivalence due to sibling envy. His twin brother was treated as the baby, being some thirty-three minutes younger. On the Oedipal level he was envious of the father from whom he wanted the Oedipal mother. His preoedipal conflicts were used as a defense against Oedipal strivings. He cheated father and brother in his transference relationships as he felt they had cheated him in childhood. His sense of unity with his twin led to conflicts of ego identity since he sought to free himself from this bond, yet felt incomplete without it. The author used a successful parameter in this therapy. He gave sessions of two hours duration, for the patient felt cheated in the usual one-hour session since unconsciously half of it belonged to his brother. He retaliated by keeping material from the analyst. The two-hour session made him feel as if he were receiving his just due.