With regard to pregnancy check in cattle, it is an important and challenging task to ensure a reliable diagnosis as early as possible. Incorrect diagnoses can lead to enormous economic losses and may result in financial requests. Another problem is that cows diagnosed as pregnant may not be able to maintain pregnancy due to the high incidence of embryonic mortality. All methods for pregnancy diagnosis, e. g. transrectal palpation or ultrasonography, as well as laboratory based pregnancy tests have advantages and disadvantages. It has to be noted that the reliable diagnosis of "pregnant" and "non pregnant" is often not possible, especially early (28-30 days) after artificial insemination ("questionable diagnosis"). A reexamination might be an option in those cases. On the other hand, a concurrent laboratory based pregnancy test in cows with questionable transrectal or ultrasonographic findings may also allow a secure diagnosis and may in addition be an option to recognize animals with problems early.