Using flow cytometry (FC) with a AF647-labelled Hu4-2-17-LC clone, we analyzed whole blood and frozen samples from CLL and HCL cases to confirm previously published ROR1 prevalence [4–6], adding more information to the infrequent HCL type that accounts for 2% of all leukaemias [5, 11]. Here, ROR1 is linked to hairy cell leukemia.