Abstract: A blood analyzer having a blood cell sedimentation control mechanism is disclosed, which includes a cassette receiving interface including a cassette compartment and a blood sensor operable to detect a presence of blood in a disposable cassette removably disposed within the cassette compartment; a system control electrically connected to the blood sensor, and a blood measurement assembly connected to the system control and adapted to connect with the disposable cassette. The system control includes a time recording mechanism and a predetermined sedimentation time control criterion. Further disclosed is a method of controlling blood cell sedimentation during sample preparation process on the blood analyzer.