Mixed states have had growing importance since Kraeplin. They have long contributed to the concept of bipolar disorder. They are frequent, occurring in 1/3 of all bipolar episodes. Many severe psychotic mixed states are still misdiagnosed and mistreated as schizophrenia. Because they have such complex presentations, they represent a challenge to diagnosis and treatment.

The authors' aims are to report a mixed episode; to describe its fast improvement only when lithium was introduced and to compare this result with the evidence in current guidelines.

A patient clinical file was analyzed. Literature research was performed. Relevant chosen papers were selected.

Women. 33. Actress. Gradual depressive simptoms, after broke up with her boyfriend the month before. She became suspicious, showing persecutory ideias. She was thin, unable to sleep, her house was disorganized. On admisson she was agitated, her eyes sad, her face almost inexpressive, her speech disconected. She showed great instability: she seemed depressive, then loughed inexpectedly, suddendly became coprolalic. She was diagnosed borderline personality before. She has positive psychiatric family history (mother, psychotic depression). After valproate, bupropion and olanzapine her humor and judgment improved but she kept an unstable behaviour. Lithium´s introdution enabled a fast, sharp recovery and organized behaviour.

Despite the prevalence of mixed states, research into the eficacy of treatments is limited. Current guidelines lack specific treatment recommendations and are sometimes inaccurate. Further studies are needed to complete our knowledge´s gap in the treatment of mixed states.