Atypical antipsychotic drugs (AADs) induce weight gain, truncal adiposity and may engender a metabolic syndrome which may progress to IFG/IGT or DM. AADs effects in lean schizophrenic patients without metabolic syndrome are not documented, especially the relationship between weight gain and changes in insulin sensitivity (S), beta-cell function (β), and circulating adiponectin. We prospectively determined the outcome of 9-month therapy with AADs on anthropometrics, metabolism and adiponectin, including HOMA-modeling of S, β, and βxS (hyperbolic product, assessing individual β adjusted for S)in 36 schizophrenic subjects (M:F 24:12; Caucasian n=23; North-African n=12; South-Asian n=1) aged 35±9 years (mean±1SD) free of MetS (NCEP-ATPIII).