Abstract: A device for automatic preparation of blood smears on plates comprises a storage unit for stacked new plates, an extractor unit to extract a plate from the stack, a depositing unit. To deposit a drop of blood on a plate, a spreading unit, to spread a drop of blood and produce a blood smear, a marking unit, comprising a marking head which can place means of identification on a reserved area of the plate, a drying unit, which can dry the blood smear, a coloring unit), which can color the blood smear, an output unit to unload the plate, and transfer means, to displace the plate between the aforementioned units, according to a pre-determined path.