Treatments given to patients with primary psychotic disorders include mood stabilizers (MSs) combined with other psychotropics, despite the limited evidence of efficacy, safety, and lack of regulatory approval. We analyzed records of 636 inpatients at the McLean Hospital (2002–2009), who were diagnosed with bipolar disorder (n=318), a schizoaffective disorder (n=210), or schizophrenia (n=108), to evaluate MS-usage, drug-selections, combinations and doses, improvement, adverse-effect risks, associated factors, and secular trends. Between 2002 and 2009, the use of MSs increased from 53 to 94% of patients, MSs per patient increased by 74%, and the total final doses (lithium-equivalents in milligrams/day) increased by 35%. The most commonly prescribed MSs ranked: valproate, lithium, lamtogrine. With the use of MSs, the duration of hospitalization was longer by an average of 18%, Clinical Global Impression ratings improved by 55%, and adverse-effects risk was lower by 22%. In multivariate logistic modeling, treatment with a MS was associated with: (i) most recent year of sampling, (ii) more psychotropics per patient at discharge, (iii) diagnosis (schizophrenia < schizoaffective or bipolar disorders), (iv) longer period of hospitalization, and (v) somewhat younger age. MSs, usually in combination with antipsychotics, were used increasingly for inpatients over the past decade, including for patients with primary psychotic disorders. The effectiveness and safety of this practice remain to be evaluated adequately.