A pilot study was conducted to evaluate the effect of nizatidine on olanzapine-associated weight gain (OAWG) in ten patientswith schizophrenia and schizophreniform disorder in Korea. Psychometric ratings with positive and negative syndromescale (PANSS) and brief psychiatric rating scale (BPRS) were measured at baseline, week 4 and week 8; as were weight and bodymass index (BMI). A combination of nizatidine for 8 weeks resulted in significant reversal of weight gain without worsening thepsychopathology (weight: 3.5% and BMI: 3.7%). In line with studies of Western populations, an add-on therapy of nizatidinecould be an effective option for the control of weight gain in olanzapine-treated patients in Korea. Our findings call for furtherevaluation of the effect of this drug on OAWG, with randomized placebo-controlled studies, in Asian populations.