The essential feature of male erectile disorder, according to DSM-IV (American Psychiatric Association 1994), is a persistent or recurrent inability to attain, or to maintain until completion of the sexual activity, an adequate erection. Another important aspect and diagnostic criterion is that the disturbance must cause marked distress or interpersonal difficulty. The disturbance cannot be better accounted for by another Axis I disorder (except another sexual dysfunction), and it must not be due to the direct physiological effects of a substance (including medication) or a general medical condition.

DSM-IV further states that occasional problems with having erections that are not persistent or recurrent or are not accompanied by marked distress or interpersonal difficulty are not considered to be male erectile disorder. A diagnosis of male erectile disorder is also not appropriate if the erectile dysfunction is due to sexual stimulation that is not adequate in focus, intensity, and duration. Older males may require more stimulation or take longer to achieve a full erection. These physiological changes should not be considered to be male erectile disorder.

The latter part of the DSM-IV discussion of male erectile disorder - actually, specification of what is not male erectile disorder - underscores the importance of thorough evaluation and of patient psychoeducation and psychotherapy.