Objectives: Transurethral intraprostatic ethanol injec- tion (TIIE) ex vivo to bull prostate and in vivo experiments on dogs to study the effect of ethanol on prostate tissue and the relationship between the volume of injected etha- nol and the size and shape of the intraprostatic lesion. Material and methods: In ex vivo experiments the prosta- tes of six bulls were used. Into the prostate tissue 1, 3 and 5 ml ethanol was injected. The preparations were divided by several transverse sections and individual lesions were measured. The experiment was repeated in vivo on 12 dogs. The prostates with surrounding tissues were extir- pated 6 hours (n = 5), 7 days (n = 2) and 21 days (n = 5) after operation. Results: Ex vivo experiment – instillation of 1 ml ethanol causes a lesion 5.23*, 1.03 in diameter, injection of 3 ml ethanol a lesion of 11.8* 1,88 mm and injection of 5 ml a lesion of 15.43*, 3.67 mm. The capsule of the prostate remained intact. Acute in vivo experiments – lesions cau- sed by injection of 1 and 2 ml absolute alcohol have an irregular shape, dimensions 0.5 x 0.5 x 0.4 and 0.7 x 1.0 x 0.8 cm. Injection of 3 ml caused an oval lesion 1.1 x 1.5 x 1.0 cm reaching as far as the prostatic capsule which remained intact. Chronic in vivo experiment: 7 and 21 days after TIIE the authors observed in the prostate necrotic foci and cavity formation. Multiple ethanol in- jections led to marked dilatation of the urethral lumen. No complications associated with TIIE were observed. The systemic effect of ethanol was minimal. Conclusion: Intraprostatic ethanol injection into the pros- tate leads to ablation of prostatic tissue. It does not damage the prostatic capsule and the ethanol effect rema- ins restricted to prostate tissue. The striated muscle ureth- ral sphincter, urinary bladder wall and periprostatic tissue remained intact in all experimental animals. The presented experimental results indicate the possible po- tential of TIIE in the treatment of benign hyperplasia of the prostate.

        Key words: chemoablation of the prostate, transurethral