Background The pattern of symptom response to second generation antipsychotics (SGAs) has not been studied extensively. Understanding the time course of symptom response would help to rationally monitor patient progress. Objective To determine the short-term differential time course of response of symptom dimensions of first episode schizophrenia viz., negative, positive symptoms and 5 factors of anergia, thought disturbance, activation, paranoid-belligerence and depression to treatment with SGA olanzapine. Methods 57 drug naive patients with schizophrenia were treated for 4 weeks with olanzapine 10 mg/day, increased to 20 mg/day in 1 week. Weight was recorded and ratings with the Positive and Negative Syndrome scale (PANSS), the Simpson Angus Scale (SAS) were performed weekly. Results 43 patients completed 4 weeks of assessment. Scores on all of the dimensions improved. By the end of week 1, only positive syndrome, thought disturbance and paranoid-belligerence dimensions improved. Maximum improvement was seen with paranoid-belligerence by week 1, followed by positive syndrome in week 2, and depression at week 3. The percentage improvement in positive syndrome was significantly greater than negative. Over 4 weeks there was a mean weight gain of 2 kg and there were significant extrapyramidal symptoms. Conclusions Olanzapine produced reduction in all dimensions, but the pace of responding of individual dimensions differed. Longer-term studies comparing SGAs with first generation antipsychotics are needed.