The five-axis measuring systems are one of the most modern inventions in coordinate measuring technique. They are capable of performing measurements using only the rotary pairs present in their kinematic structure. This possibility is very useful because it may cause significant reduction of total measurement time and costs. However, it was noted that high values of measured workpiece's form errors may cause significant reduction of five-axis measuring system accuracy. The investigation on the relation between these two parameters was conducted in this paper and possible reasons of decrease in measurement accuracy was discussed in example of measurements of workpieces with form errors ranging from 0,5 to 1,7 millimetre.