We examined the acceptability and diagnostic accuracy of dynamic ultrasound images transmitted at 128 kbit/s and 384 kbit/s. The gold standard was the direct recording of 200 ultrasound examinations on video-tape. The taped images were later transmitted at both 128 kbit/s and 384 kbit/s and recorded, resulting in three tapes for each case. Four observers viewed each tape individually. Ninety per cent of images transmitted at 384 kbit/s were rated as diagnostically acceptable compared with 32% of images transmitted at 128 kbit/s. Diagnostic agreement between tapes transmitted at 384 kbit/s and the gold standard was 85%, compared with 78% for 128 kbit/s transmissions. Observers were not satisfied with low-bandwidth transmission of ultrasound images despite adequate diagnostic accuracy. Dynamic ultrasound images transmitted at 384 kbit/s were viewed as both diagnostically acceptable and accurate.