Long non-coding RNAs (lncRNAs) have crucial roles in regulation of many aspects of cell functions which are related with carcinogenesis process. The lncRNA Opa Interacting Protein 5-antisense 1 (OIP5-AS1) is among lncRNAs whose roles in some human malignancies have been elucidated. In the current study, we aimed at identification of the role of this lncRNA in bladder cancer. Expression level of OIP5-AS1 was assessed in 50 bladder cancer tissues, the corresponding adjacent non-cancerous tissues (ANCTs) and 30 normal bladder tissues using quantitative real time PCR. OIP5-AS1 was significantly down-regulated in tumor tissues compared with normal bladder tissues (expression ratio=0.14, p=0.008). However, there was no significant difference in its expression between tumor tissues and ANCTs (expression ratio=1.79, p=0.23). No significant association was detected between relative expression of this gene and clinicopathological data of patients. Based on the area under curve (AUC) value, the diagnostic power of this gene was estimated to be 0.67. OIP5-AS1 expression levels might differentiate bladder tumor tissues from normal bladder samples but not from ANCTs.