To test whether the two immunohistochemical markers (GATA3 and KRT5/6) could be used for the molecular classification of bladder cancer in daily pathology practice, we performed immunohistochemical stains for GATA3 and KRT5/6 on regular FFPE routine histologic tissue sections (n = 74) that were matched to the original MDACC cohort of fresh frozen tissue samples in which the molecular subtypes were assessed by mRNA expression levels. Here, KRT5 is linked to urinary bladder carcinoma.