This study investigates whether the augmentation of cognitive behavior therapy (CBT) with fluoxetine improves outcomes in anxious school refusing adolescents (11-16.5 years). Sixty-two participants were randomly allocated to CBT alone, CBT + fluoxetine or CBT + placebo. All treatments were well tolerated; with one suicide-attempt in the CBT + placebo group. All groups improved significantly on primary (school attendance) and secondary outcome measures (anxiety, depression, self-efficacy and clinician-rated global functioning); with gains largely maintained at 6-months and 1-year. Few participants were anxiety disorder free after acute treatment. During the follow-up period anxiety and depressive disorders continued to decline whilst school attendance remained stable, at around 54 %. The only significant between-group difference was greater adolescent-reported treatment satisfaction in the CBT + fluoxetine group than the CBT alone group. These results indicate the chronicity of school refusal, and the need for future research into how to best improve school attendance rates.