Anejaculation is the pathological inability to ejaculate despite an erection^[1] in males, with (orgasmic) or without (anorgasmic) orgasm.

It can depend on one or more of several causes, including:

• Sexual inhibition
• Pharmacological inhibition. They include mostly antidepressant and antipsychotic medication, and the patients experiencing that tend to quit them^[3]
• Autonomic nervous system malfunction
• Prostatectomy - surgical removal of the prostate.
• Ejaculatory duct obstruction
• Spinal cord injury causes sexual dysfunction including anejaculation. The rate of being able to ejaculate varies with the type of lesion, as detailed in the table at right.
• Old age
• Diabetes mellitus^[1]

Anejaculation, especially the orgasmic variant, is usually indistinguishable from retrograde ejaculation. However, a negative urinalysis measuring no abnormal presence of spermatozoa in the urine will eliminate a retrograde ejaculation diagnosis. Thus, if the affected person has the sensations and involuntary muscle-contractions of an orgasm but no or very low-volume semen, ejaculatory duct obstruction is another possible underlying pathology of anejaculation.^{[citation needed]}