Objectives We investigated the effectiveness and safety when treated in schizophrenics with paliperidone palmitate, a long acting injectable antipsychotic. Methods This was a 24-week open-label study, performed at one center in Korea. The eligible patients with schizophrenia diagnosed by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) criteria were enrolled. Patients received long-acting paliperidone palmitate injection (234 mg, baseline; 156 mg, week 1 ; then once 4 weeks flexible dosing). Effectiveness assessments were measured by the Positive and Negative Syndrome Scale (PANSS), The Clinical Global Impression Severity Scale (CGI-S), The Personal and Social Performance (PSP) at baseline, week 1, every 4 weeks untill 24 weeks or endpoint. Safety assessments were measured by The Extrapyramidal Symptom Rating Scale (ESRS), body weight (BW) and incidence of adverse events. Oral antipsychotics were stopped or tapered off within next 14 days. Results Of 20 patients recruited, 9 patients (45%) completed the study. Paliperidone palmitate produced a significant improvement in PANSS total score from baseline to endpoint. The response rate was 75% [mean change (${pm}SD$) $-25.9{pm}14.4$, all p < 0.001]. The CGI-S and PSP total scores significantly improved during 24 weeks (All p < 0.001). Eighty percent of patients reported adverse events and most common adverse events (${geq}10%$) in paliperidone palmitate were anticholinergic adverse event, extrapyramidal symptoms, weight gain, akathisia, insomnia, headache, agitation, anxiety and GI trouble. ESRS score is not statistically significant, but tends to get better at the end of the study when compared to baseline. Conclusions Our study results demonstrated maintained effectiveness and safety of paliperidone palmitate treatment in schizophrenics. And provides both clinicians and patients with a new choice of treatment that can improve the outcome of long term therapy. Their potential effectiveness and safety should be better addressed by future randomized-controlled trials.