The clinical value of the current Diagnostic and Statistical Manual of Mental Disorders diagnosis of adjustment disorder is controversial. The aim of this article is to review the literature on adjustment disorder and to present suggestions for the improvement of this diagnostic category in future classification systems. The literature utilized for this review was retrieved by MEDLINE (1967 until May 2009) and was supplemented by a manual search of the literature. The analysis of the literature indicates that the diagnosis of adjustment disorder is not characterized by consistent clinical description and prognosis, adequate differentiation from other disorders, or specific psychometric and neurobiologic features. The spectrum of affective disturbances entailed by the diagnosis of adjustment disorder appears to be too broad. A major problem seems to lie in the fact that it is an exclusion diagnosis that overlaps with subthreshold manifestations of mood and anxiety disorders. More precise characterizations of stress-related disturbances are available.