Obstructive uropathies are among the most Frequent predisposing factors in urinary infection. We have reviewed the frequency of pathogenes causin urinary infection in obstructive uropathies. We have exmined 259 patients with prostatic adenoma and urinary calculosis prior and after the operation during the years 1986 and 1987. The most frequent are bacteria: Proteus, Pseudomonas, Klebsiella and E. colli. Proteus was the most frequent (35.2 p.c.), and then Pseudomonas (24.5 p.c.) and E. coli (10 p.c.). Prostatic adenoma is frequent cause of urinary obstruction, and thus the urinary infection is more frequent in males.