Objective To evaluate the clinical application of 3 D ultrasound in the diagnosis of bladder diseases. Methods In 21 patients with bladder disease,3 D images were studied with a Voluson 530D diagnostic system.At first,the two dimensional images of lesions were collected,then defined 3 D volumes of interest were stored,reconstructed and analyzed. Results 3 D ultrasound provided a clear stereoscopic view and depicted the appearance of the 21 bladder diseases,displayed the internal structures,and showed invasive depth within and outside the bladder wall and also metastasis of the adjacent organs. Conclusions 3 D ultrasound can clearly demonstrate the morphologic characteristics and internal structures of the bladder disease and provide much more reliable information for the diagnosis of diseases.