The potential effect of repetitive transcranial magnetic stimulation (rTMS) on core positive and negative symptoms in schizophrenia has not yet been clearly established. The aim of this study was to examine the efficacy of adjuvant 10 Hz, suprathreshold left prefrontal rTMS in negative symptoms of schizophrenia in a double-blind sham-controlled design. Additionally, our study also investigated the suitability of applying the same stimulus condition on positive symptoms. Ten right-handed schizophrenia patients received sham or active 10 Hz suprathreshold rTMS to the left dorsolateral prefrontal cortex with psychopathology, depression and global improvement ratings before and after rTMS sessions. Compared to sham, active rTMS significantly improved negative symptoms, irrespective of change in depressive symptoms.