OBJECTIVES: Residential services costs have been associated with multiple variables such as resident psychiatric status and severity of symptoms, daily living skills, social behaviour problems, geographic region, service size, gender and age. In 2008, up to twenty full staffed homes were created in Sao Paulo city, in order to accommodate people discharged from psychiatric hospitals. Aims of this study were to estimate the direct costs of staffed homes and also to explore the relationship between resident profile and services costs. METHODS: We used a bottom-up approach for the estimation of direct costs according to public health service provider perspective. Direct costs included costs with accommodation, inpatient, outpatient and emergency health services and treatment received in the previous month, in 147 subjects with mental disorders living in twenty full staffed homes during the year 2011. We evaluated resident profile (quality of life, social behaviour problems, psychiatric diagnosis, severity of symptoms, socio demographic characteristics) and pattern of health service use. Linear regression analysis was employed to verify the effect of resident profile on residential services costs. RESULTS: Residential services costs corresponded to 89% of the total direct costs including accommodation, health care and medication, and of these, 62% were due to human resources costs, 8% to transportation and house repairs and 7% to overhead. Residential costs were associated exclusively with geographic region, length of time living in psychiatric hospital and length of time living in residential service. Mean of residential costs per month per capita was U$1,750.00 (1U$= 2.00 R$-Brazilian currency). One-fourth to one-third of the sample presented good scores of autonomy, social behaviour and psychiatric status.  CONCLUSIONS: Direct costs of residential services could be optimized if one-fourth of sample with good autonomy and appropriate social behaviour would be transferred to less expensive services like semi-staffed or not staffed homes.