Cone penetration tests (CPT) is one of the most sophisticated geotechnical field investigations methods. As for all test methods, the CPT is associated with many uncertainties. However,there are two main sources that have aninfluence on the quality ofCPTumeasurements. One is the choice of equipment since different equipment differs in design and functionality.The other source relates tooperator performanceand incorrectexecutionof the methodas well as lack of competence to analyze the results.However, inorder to achieve satisfying results, the operator should be skilled, competent and well-educated. Some countries don’t have any formal education and in countries wereformal education doexist, the achieved quality ofresultsdoesquite frequentlystill come out unsatisfactory.This fact is seldom mentioned, but still a well-known fact amongst practicing geotechnicians.The objective of this paperis to discuss operator performance related factors and contribute to a better knowledgeof how important every single procedure contributes to the outcome as well as quality of the results.