This report describes investigations of the dosing behaviour of piston-stroke pipettes and microlitre syringes when dosing different liquids. The dosed volumes were in the range between 0.2 µl and 50 µl, they were measured with a gravimetric measuring apparatus. The liquids used were water, ethanol and nonane, with a special focus on investigating the dosing behaviour of human serum. In the course of the investigations, the gravimetric measuring method was also compared experimentally with the photometric method. In order to enable gravimetric calibrations of volume dosing devices with human serum in analytical laboratories, a simple method for determining the density of human serum from the analytically determined saline and protein concentrations in the serum was developed.