In 753 uropathogenic strains of E. coli isolated from urine of patients with urinary tract infections in two localities the authors assessed O and H antigen, mannosensitive adhesin and haemolytical capacities. In strains with assessed O antigen and some of the strains where it was not assessed the authors searched for P fimbriae and for orientation for X adhesin. O antigen was assessed using 33 antisera in 52.05% of the strains. A leading position in the group was held by group 06 (12.21% of all strains). The latter was followed by groups 02, 01, 04, 08, 018 and 021 which together accounted for more than one quarter of all strains. In a large number of O groups the authors found more than one H antigen. Mannosensitive adhesin was found, as expected, in the majority of strains (87.25%). Its absence in more than half 050 strains and in almost one third of 01 strains was striking. 37.18% of all examined strains had haemolytic capacities. 61% of all haemolytic strains belonged only to six O antigenic groups 06, 04, 02, 075, 018 and 021. P fimbriae and X adhesin were assessed in 456 strains. The presence of P fimbriae was proved in 27.41% strains, 72% of all strains with P fimbriae belonged to antigenic groups 01, 02, 04 and 06. X adhesin was detected in 8.33% strains. Of these more than one quarter were formed by strains 021. In strains of this antigenic group we did not detect, however, any P fimbriae. The achieved results do not only inform on some properties of uropathogenic strains of E. coli isolated in some parts of our territory; they indicate also that by means of the applied tests it is possible to obtain a very differentiated picture of these strains. This may be used everywhere where it is desirable to search for groups of strains with homogeneous properties or to obtain at least approximate information on their virulence.