Early-onset Bipolar Disorder (BD) appears to be associated with worse outcome, persistent mood şuctuation, severe psycosocial impairment, and slow response to treatment. Recurrencies and remissions could mostly be seen together in the course of BD. There are many evidences suggesting that childhood-onset BD is associated with greater familial loading for affective illness than adult-onset BD. Attention Deficit Hyperactivity Disorder (ADHD) is the major problem in differential diagnosis in prepubertal and early adolescent subjects. This problem stems from a very high prevalence of comorbid ADHD in subjects with childhood-onset BD and from the overlap of the DSM-IV criteria for mania and ADHD. Psycotherapeutic and pharmacologic interventions are required in treatment of children and adolescents with BD. Treatment modalities for early-onset mania are evolving. At this time, there is more evidence for the efficacy of atypical antipsychotics than for lithium or anticonvulsants. . In this case report, clinical features and follow-up process of an adolescent with treatment resistance and very early-onset BD will be discussed in literature. 14-year-old girl, who applied to Dokuz Eylul Medical School Child and Adolescent Psychiatry Inpatient Unit was hospitalized urgently with symptoms of aggresiveness, increasing energy and movements, irritability and persecutory delusions. She was diagnosed to have BD two years ago as she has been on şoow up for ADHD and Disruptive Behaviour Disorder with using stimulants, multiple antipsychotics in another psychiatry clinic for 5 years. In family history her cousin already has early-onset BD and in assessment process her father was diagnosed to have BD. Within two years, her symptoms have been succeeded to be slowed down for only once by using risperidone, quetiapine and valproate. But after 3 months, her symptoms remitted and could not be regressed with multiple antipsychotics and an antimanic drug (YMRS:42). After hospitalization, her dysphoric mood could not be managed and then, clonazepam and zuclopenthixol acetate depot was injected 2 times in a week. After that, dystonia, difficulty of swallowing, hypersalivation, parkinsonism especially by walk, severe tremor appeared and biperiden dose was rearranged (YMRS:38). Because of lessened response to valproate and antipsychotics, lithium treatment was started. Three weeks later, persecutory delusions disappeared, increased energy started to decrease and irritability disappeared (YMRS:19). After 4 weeks on 900 mg lithium, hypothyroidism has emerged and treatment was supported with levothyroxine. We aimed to present a case with very early onset BD, who also has many comorbidities, high family loading of BD and less response to many psychotropics. After many different trials of antipsychotics and valproate, lithium treatment was the most useful intervention for this case. We underlined the treatment effects of lithium for early-onset BD in this case presentation.