Dipeptidyl peptidase IV is known to be involved, due to both hydrolytic and non-hydrolytic mechanisms, in various cell functions of normal and cancer cells as well. In this report dipeptidyl peptidase IV substrate and pH preferences, some inhibition parameters, freezing/thawing sensitivity and stability against hydrolysis by trypsin were studied in C6 rat glioma cells. Our results confirmed substantial heterogeneity of dipeptidyl peptidase IV population. Such observation is important to avoid methodological artifacts and to decrease risk of misinterpretations in biological studies.