Abstract Background The use of intestinal ultrasonography (IUS) is recommended for suspected or known inflammatory bowel disease (IBD), but the technique is challenging to learn. This prospective study examined how the accuracy of IUS increases with operator experience (“learning curve”) and if prior abdominal ultrasound experience facilitates the learning process. Methods The study included five gastroenterologists: four trainees and one expert sonographer. Two trainees had limited abdominal ultrasound experience (< 50 exams) and two had extensive experience (> 500 exams); none had IUS experience. The trainees received an eight-hour course on IUS and one week of hands-on training with the expert sonographer on approximately 50 IUS exams. Thereafter, over a four-week period, each trainee performed 99 examinations and reported four IUS findings. The expert sonographer repeated the exam, and concordance (k) between the expert and trainees was assessed in three consecutive testing periods of 33 exams each. Results A progressive improvement in concordance was observed for all IUS findings from Period 1 to Period 3, overall and for both groups of trainees, although those with experience in abdominal ultrasound had faster learning curves. The minimum number of examinations required to achieve concordance with the expert operator (after the initial 50 exams) for detecting increased bowel wall thickness was 34 and detecting bowel dilatation was 29. However, a minimum of 47 examinations was necessary to achieve concordance for detecting intra-abdominal complications, considered an advanced IUS competence. The number of examinations required to achieve concordance was higher for trainees without than with abdominal ultrasound experience. Conclusion Basic competence in IUS can be acquired with relatively few examinations, while advanced competence requires more extensive training, particularly for gastroenterologists without abdominal ultrasound experience. These findings have implications for the development of training programs and the establishment of proficiency levels in IUS.