In the diagnostic ultrasound (US) transducer technology, the high frequency US(HFUS) transducer over 20 MHz is one of the current issues to be pursued for better resolution with the expense of penetration. HFUS single element transducers and the mechanical scanning systems for imaging are reviewed, and HFUS array transducers are also briefly summarized. HFUS applications such as the human applications in ophthalmology and dermatology and small animal applications for research purposes are reviewed with vascular and blood imaging in this paper.