The research of neurobiology and treatment of various disorders requires certain degree of homogeneity of the studied entities. In an ideal word, common etiology and/or pathogenesis would help to define homogenous entities. As our understanding of etiology and/or pathogenesis of mental disorders and diseases is lacking, we rely on various diagnostic systems to help us reach some degree of homogeneity.

The diagnostic criteria of sexual dysfunction(s) in the DSM-IV are rather vague and imprecise. Interestingly, we are not even clear when a sexual problem becomes a sexual dysfunction. As the new versions of the diagnostic systems (e.g., DSM-V) are being prepared, the classification and definitions of sexual disorders/dysfunctions are being considered.

The general classification issues that need to be and are addressed are specific duration of sexual dysfunctions, use of distress s a diagnostic criterion and quantification of severity and frequency. Strengthening and clarifying these three classification issues would probably help in defining more homogenous entities.

The broader yet more specific issues to be considered are inclusions of new diagnostic entities (persistent genital arousal disorder in women; adjustment disorder with disturbed sexual functioning; coercive paraphilic disorder), possible removal or reclassification of some sexual dysfunctions (e.g., sexual aversion disorder - remove or reclassify as specific phobia); collapsing some entities into one (dyspareunia and vaginismus into genitor-pelvic pain/penetration disorder) changing the names of some dysfunctions (premature ejaculation to rapid ejaculation); and redefining some dysfunctions (e.g. sexual desire and subjective sexual arousal in women).