Long noncoding RNAs ( lncRNAs) are a group of noncoding RNAs of more than 200 nucleotides in length. Accumulating research has unearthed increasing evidence that lncRNA wass are widely involved in the regulation of pathophysiological processes and affect the establishment and progression of human diseases including cancers. HAGLR opposite-strand lncRNA is highly expressed in many tumors, playing important roles in regulating tumors’ malignant behaviors. This paper reviews the expression and mechanisms of action of the HAGLR opposite-strand lncRNA in tumors.