The aim of this study was to evaluate changes in long-term health care costs and symptom severity after adjunctive intensive short-term dynamic psychotherapy (ISTDP) individually tailored and administered to patients with bipolar disorder undergoing standard psychiatric care. Eleven therapists with different levels of expertise delivered an average of 4.6 one-hour sessions of ISTDP to 29 patients with bipolar disorders. Health care service costs were compiled for a one-year period prior to the start of ISTDP along with four one-year periods after termination. Two validated self-report scales, the Brief Symptom Inventory and the Inventory of Interpersonal Problems, were administered at intake and termination of ISTDP. Hospital cost reductions were significant for the one-year post-treatment period relative to baseline year, and all cost reductions were sustained for the follow-up period of four post-treatment years. Self-reported psychiatric symptoms and interpersonal problems were significantly reduced. These preliminary findings suggest that this brief adjunctive psychotherapy may be beneficial and cost-effective in select patients with bipolar disorders, and that gains may be sustained in long-term followup. Future research directions are discussed.