The assesment of lymph nodes for the presence of tumour dissemination is an important aspect of the clinical evaluation of patients diagnosed with renal tumours. However, the identification of micrometastases can prove challenging. Now, data from a proof-of-principle study demonstrate that flow cytometry following immunohistochemical staining of lymph node samples for carbonic anhydrase 9 and cadherin-6 enables the detection of mircometastases: in the five patients whose lymph node samples were investigated in this study, four had micrometastases that were not detected using conventional examinations.