We investigated the relationships between L/S promoter (SERTPR) and l/s intron2 (SERTin2) genetic variants of serotonin transporter (SERT) polymorphisms with olanzapine-induced weight gain and treatment response in 94 female schizophrenic patients treated with olanzapine for up to 3 months. Body mass index (BMI) was calculated for each patient prior to olanzapine administration and 3 months afterwards. To assess and evaluate improvement of clinical psychotic symptoms and therapeutic response to the antipsychotic, all patients were rated using the Positive and Negative Syndrome ScaLe (PANSS). Overall, the presence of S SERTPR allelic variant and SS genotype was associated with significantly higher weight gain in subjects who were non-obese at the time of admission. The presence of L SERTPR variant was associated with significantly better treatment response measured with total PANSS and general PANSS subscale, while the presence of l SERTin2 variant determined better treatment response only in several items. No evidence of linkage disequilibrium between the two loci was found in the sample. These findings identify genetic factors associated with oLanzapine-induced weight gain and treatment response in femaLe schizophrenic patients.