The N 6 -methyladenosine (m 6 A) modification is the most common modification of messenger RNAs in eukaryotes and has crucial roles in multiple cancers, including in urological malignancies such as renal cell carcinoma, bladder cancer and prostate cancer. The m 6 A RNA modification is controlled by three types of regulators, including methyltransferases (writers), demethylases (erasers) and RNA-binding proteins (readers), which are responsible for gene regulation at the post-transcriptional level. This Review summarizes the current evidence indicating that aberrant or dysregulated m 6 A modification is associated with urological cancer development, progression and prognosis. The complex and context-dependent effects of dysregulated m 6 A modifications in urological cancers are described, along with the potential for aberrantly expressed m 6 A regulators to provide valuable diagnostic and prognostic biomarkers as well as new therapeutic targets.