Objective: To evaluate the safety, tolerability, and benefit of fluvoxamine for the treatment of major depressive disorder or anxiety disorders in children and adolescents with cancer. Method: The study was conducted from 2001 to 2004 at a pediatric hematology-oncology center. Fifteen children and adolescents with cancer were treated with fluvoxamine 100 mg/day in an open prospective 8-week trial. Safety and tolerability were evaluated at baseline and at weeks 4 and 8 by blood tests and the Side Effects Checklist. Clinical benefit was assessed with the Clinical Global Impressions-Improvement, the Children's Depression Rating Scale-Revised, and the Pediatric Anxiety Rating Scale. Results: Fluvoxamine was well tolerated by all subjects. Psychiatric symptoms improved significantly. Conclusions: In this open trial, fluvoxamine appeared to be well tolerated and was associated with a promising reduction in the depression and anxiety symptoms of pediatric patients with cancer.