BACKGROUND: This case illustrates previously undiagnosed dissociative identity disorder (DID) in a middle-aged female with extensive childhood trauma, who was high functioning prior to a trigger that caused a reemergence of her symptoms. The trigger sparked a dissociative state, attempted suicide, and subsequent inpatient psychiatric hospitalization. OBJECTIVE: Practitioners should include in their differential and screen for undiagnosed DID in patients with episodic psychiatric hospitalizations refractory to the standard treatments for previously diagnosed mental illnesses. DESIGN: Case study. RESULTS: During hospitalization, the diagnosis of DID became apparent and treatment included low-dose risperidone, mirtazapine, sertraline, unconditional positive regard, normalization of her dissociative states in an attempt to decrease her anxiety during treatment, and documentation for the patient via written notes following interviews. CONCLUSION: These methods helped her come to terms with the diagnosis and allowed the treatment team to teach her coping skills to lessen the impact of dissociative states following discharge.