Transmission (TM) sonography allows a reliable and fast imaging of soft tissues like joint capsules and tendons, especially of hands and feet. Bony structures appear blurred, but serve as landmarks for easy orientation on the ultrasonic images. The quality of imaging allows a reproducible measurement of joint capsule parameters. Inflammatory alterations of joints are recognized earlier than with conventional x-rays. TM sonography contributes to the diagnostic panel for rheumatic diseases, which involve soft tissues and joints of hands and feet. Today, TM sonography cannot compete with conventional reflex sonography in general arthrosonography, but it is an interesting addition. Follow-up studies will show whether objective joint parameters available by TM sonography may help to both indicate disease progression and to monitor therapeutic interventions in rheumatic diseases.