The value of angiography and fine needle aspiration biopsy in detecting, grading and staging of renal tumours was studied in 55 patients with renal tumours suspected clinically or on urography. 42 patients had malignant tumours. A correct angiographic diagnosis was made in 94% of the renal adenocarcinomas, the corresponding percentage for the aspiration biopsies was 71%. A combination of angiography and cytologic examination gave the correct diagnosis in 97%. In 4 cases of renal pelvic carcinoma the angiography showed extensive hydronephrosis only, the final diagnosis in these was cases achieved by fine needle aspiration biopsy. Angiographic staging of 30 renal adenocarcinomas was made according to the TNM system. The radiological staging was correct in 30% of T3 tumours, but in only 50% of T1 tumours and in one out of five T2 tumours. The difficulties seemed to be in determining the relation of tumours situated marginally near the renal capsule. Angiographic grading of the tumour was made according to the vascular pattern and the time of venous filling. Sparse vascularity and venous filling time of over 5 seconds was found in highly differentiated carcinomas and abundant vascularity and fast venous filling in neoplasms of moderate or low differentiation. The cytologic grading correlated fairly well with the histological grading. This study shows that angiography combine with fine needle aspiration biopsy provides good facilities for obtaining a correct diagnosis in renal tumours and preoperative information of the extent and degree of differentiation of renal malignant tumours.