The aims of our research were: estimation of asymptomatic bacteriuria (a.b.) incidence in population of women with systemic lupus erythematodes (SLE), evaluation its clinical significance and examination of bacterial colonisation of nostrils and pharynx in SLE patients with a.b. 85 women aged 24-77 (mean 49.3) with mean SLE duration 7.8 (range 1-32) years were examined. All of them fulfilled ARA criteria for the classification of SLE. Among group of patients with a.b. were counted women who had significant bacteriuria > or = 10(4) in ml urine in two cultures. Asymptomatic bacteriuria was found in 14 cases of 85 women with SLE (16.5%). In two following urine cultures bacteria from family Enterobacteriaceae were dominated: the same types of bacteria were in 85.7%--bacteriuria persistens, in others 14.3% were observed change of bacteria--bacteriuria transistens. In 9 from 14 patients with (64.3%) a.b. very massive growth of Staphylococcus aureus in culture from vestibulae of the nose swab was, in other cultures very massive growth of physiological flora was seen. All patients with a.b. were in clinical remission of SLE and they had no clinical symptoms of infection in urinary tract in 5 months of observation. However clinical significance of asymptomatic bacteriuria and pathogenic bacteria colonisation of nostrils as a precedence to symptomatic infections needs further investigations.