In this double-blind, randomized controlled study, we assessed the therapeutic effects of high-frequency left dorsolateral prefrontal cortex (DLPFC) repetitive transcranial magnetic stimulation (rTMS) on negative symptoms of schizophrenia. For the study, 117 patients with prominent negative symptoms were randomized to a 20-day course of either active rTMS applied to the left DLPFC (n = 78) or sham rTMS (n = 39). The primary outcome measures were the Positive and Negative Symptom Scale (PANSS) and the Scale for the Assessment of Negative Symptoms (SANS). Secondary outcomes included the Clinical Global Impressions Scale (CGI) and the Udvalg for Kliniske Under sogelser (UKU) Side Effect Rating Scale. We found that treatment with high-frequency rTMS for 6 weeks significantly improved negative symptoms in the active group as compared to the sham group. However, active rTMS was not correlated with significant improvement in the CGI severity of illness scale (CGI-S). The improvement of negative symptoms persisted to the 24-week follow-up assessment. These results indicate that there is a lasting beneficial effect of rTMS on negative symptoms in absence of decrease in CGI scores. We conclude that rTMS may serve as a relatively noninvasive treatment that alleviates negative symptoms in patients with schizophrenia.