A 66-year-old patient developed severe urinary stasis due to a concrement in his right ureter; foudroyant septicemia followed. Lactobacillus gasseri was grown from pyoid urine from the right renal pelvis and in two blood cultures, thus suggesting septic urinary infection caused by lactobacilli. The infection was cured by catheterisation of right ureter and antibiotic treatment with cefotaxime and amoxicillin. The concrement was removed by dissolution. Diabetes and urinary stasis appear to be the main predisposing factors for this exceptional case of septic urinary infection caused by L. gasseri.