Aims: The purpose of the study is to analyze the most frequent errors in the densitometric diagnosis of osteoporosis and to evaluate their influence on the final results of examination. Methods: On the basis of their own experience, the authors have presented here the most common errors encountered in the densitometric technique. A DPX-L densitometric apparatus (Lunar) was used in this research. Errors are divided into three groups: those dependent on the object investigated, those dependent on data analysis, and others. In the first group we took into account factors which can lead to either overestimating (+) or underestimating (−) the final result: degenerative changes (+), scoliosis (+), foreign bodies, such as metal (−), status post fracture (+), pathological structures (±), osteoporotic fractures (+), and incorrect arrangement of the investigated object (±). Errors in data analysis included erroneous data entry regarding the patient’s age, height, body mass and sex, and incorrect settings regarding the measurement field. Other errors included failure to calibrate on improper calibration of the measurement apparatus and errors in computer programs. Results: Individual errors were responsible for falsifying results from 1 to 37%. If several of these errors are accumulated, the accuracy of examination may change even more than 100%. Densitometric examinations of the lumbar spine are the most subject to error. The repeatability of the results generated by the DEXA apparatus ranges for particular skeletal regions from 0.9 to 2.5% of the CV, while the precision ranges from 3 to 5%. We also cannot exclude the impact of errors of the three types listed above on the final results. Conclusions: We are convinced that the DEXA method is an excellent instrument for the diagnosis of osteoporosis (in static bone evaluation). However; its valve diminishes in monitoring dynamic changes in bone tissue, even at 1–2-year intervals.