Clinical examples are used to illuminate several riddles of masculinity— ambiguities, enigmas, and paradoxes in relation to gender, bisexuality, and thirdness—frequently seen in male patients. Basic psychoanalytic assumptions about male psychology are examined in the light of advances in female psychology, using ideas from feminist and gender studies as well as important and now widely accepted trends in contemporary psychoanalytic theory. By reexamining basic assumptions about heterosexual men, as has been done with ideas concerning women and homosexual men, complexity and nuance come to the fore to aid the clinician in treating the complex characterological pictures seen in men today. In a context of rapid historical and theoretical change, the use of persistent gender stereotypes and unnecessarily limiting theoretical formulations, though often unintended, may mask subtle countertransference and theoretical blind spots, and limit optimal clinical effectiveness.