In this paper we attempt to show the problem of evolutionary time in two possible conceptions. On the one hand, either evolution is understood as microevolution (change of gene frequencies) or as macroevolution (speciation), the concept of time used, generally, is chronometric, i.e. time measured by a clock (months, years, thousands of years, etc.). This means that time is considered as an independent variable of the biological processes and their temporal phases simply succeed each other. But on the other hand, there is another way to understand time. If evolution is an evolutionary unit process, then evolutionary change is the modulation of a series of phases of a unit that endures. It's a qualitative time. Each evolutionary unit would have its own time. We review in the paper some possible evolutionary units (genes, populations, species, etc.) and how they are conceived temporally. Finally, we analyze more precisely the problem of evolutionary time in a species as an evolutionary unit.