Due to cognitive and learning dysfunction, schizophrenic patients with Diabetes Mellitus (DM) are more likely to control their DM poorly. A psychoeducational group is helpful for obtaining accurate knowledge and better self-care for schizophrenic patients with DM. However, few studies exploring the effectiveness of a psychoeducational group for schizophrenic patients with DM. The aim of this study was therefore to explore the effectiveness of a psychoeducational group for schizophrenic patients with DM. A one-group pretest-posttest study design was used for this pilot study. A convenience sampling was used to recruit 7 subjects being diagnosed with schizophrenia and comorbid with DM from the psychiatric day care in the regional hospital located in Northern Taiwan. All the subjects participated 8 sessions of a psychoeducational group. Study instruments included the Diabetes Knowledge Scale (DKS), Diabetes Self-Care Scale (DSC), and Group Satisfaction Scale (GSS). Non-parametric wilcoxon signed ranks test was used to compare differences in measures between pretest and posttest. Results revealed that scores on the DSC incraesed from pretest to posttest (mean=100.50, SD=38.63 v.s mean=121.75, SD=25.45) (z=-2.52, p=.012). Scores on the DKS also increased from pretest to posttest (mean=14.60, SD=2.89 v.s mean=15.80, SD=.84). However, this difference did not reach statistical significance. The mean score on the GSS was 4.23 (SD=0.80), which indicates that most of the group memebers rated their agreement on satisfaction between agree and agree uery much. Results from this pilot study generally supported the effectiveness of a psychoeducational group, and could be a reference for spychiatric mental health nurses of implementing a psychoeducational group for schizophrenic patients with DM.