Between October 1987 and October 1992 110 biopsies of transplanted kidney. Histologic examination showed 36 cases of acute rejection (Ac), 19 cases of chronic rejection (Chr), 16 cases of acute tubular necrosis (ATN) and 39 cases of cyclosporin nephrotoxicity. Sonographic characteristics as: hyperechogenicity of the cortex, hypoechogenicity of central pyelovascular zone, large and sonolucent pyramids, spherical configuration of renal allograft, were coelating with histologic and relevant clinic sings of disease. The results show statistically significant correlation with sonographic sings of acute rejection and relevant histologic and clinical findings. There was no correlations in other groups of diseases. These results confirm ultrasound as the primary imaging tool and an invaluable diagnostic modality in the renal transplant patient.