A pharmacological approach to treating patients with personality disorders (PD) is based on evidence that some dimensions of personality are mediated by variations in neurotransmitter physiology and are responsive to medication effects. Target symptoms for pharmacotherapy in the PD patient are derived from expressions of cognitive-perceptual, affective, and impulsive-behavioral dysregulation of central neurotransmitter functions. Pharmacotherapy is directed at state symptoms during periods of acute decompensation and at trait vulnerabilities, which represent the diathesis to future episodes. A basic assumption of this approach is that neurotransmitter biology transcends Axis I and Axis II definitions and that closely related symptoms may share a common pathophysiology, independent of categorical definition. A common pathophysiology implies the possibility of shared responsiveness to medication. Using a dimensional definition of symptom domains, the author has developed treatment algorithms for cognitive-perceptual symptoms, affective dysregulation, and impulsive-behavioral dyscontrol in personality disorder patients.