Atypical antipsychotics (AAPs) have led to refinements in the pharmacological management of schizophrenia and related disorders. Most AAPs produce fewer extra- pyramidal side effects than conventional agents, and appear to ameliorate "negative symptoms" to a greater degree. In general, many AAPs have a higher ratio of 5HT2 to D2 receptor occupancy than do conventional neuroleptics. This ratio may confer some of the "atypical" qualities to these agents, though regional brain selectivity may also be involved. Although clozapine and risperidone are the two AAPs clinicians now have available, many other similar agents are close to clinical development. Copyright © 1996 by W.B. Saunders Company