A 5-MHz sector transducer (experiment 1) and a 7.5 MHz linear-array transducer (experiment 2) were used for early pregnancy diagnosis in two Hungarian dairy herds under field conditions. In the first experiment, ultrasound scanning was conducted three times at 3 or 4-day intervals between 24 and 33 days after artificial insemination (AI), while in the second experiment, it was performed two times at 7-day intervals between 27 and 38 days post-insemination. Significantly more incorrect non-pregnancy diagnoses were made between 24 and 33 days (first experiment) and between 27 and 38 days (second experiment) after AI in cows in which the uterus was located far cranial to the pelvic inlet than in animals in which the uterus was located within or close to the pelvic inlet at the first ultrasonographic examination.