In 14 healthy children contrast sonography of the bladder was performed with various solutions prior to voiding cystourethrography. The solutions were introduced into the bladder via a bladder catheter. The contrast effects which occurred with iothalamate injections in the urine-filled bladder, with urine injections in the iothalamate-filled bladder, with injections of 0.9% saline solution, and with air injections into the iothalamate-filled bladder were sonographically demonstrated. In echogenicity and duration the intravesical air contrast was superior to all mixture contrasts in the bladder resulting from injections of the respective fluids.