Between 1. 1. 1988 and 31. 12. 1990, greater than or equal to 10 colony-forming units of Staph. saprophyticus were isolated from 55 of a total of 20,000 urine samples went in. The isolates from these 55 patients (52 women, 3 men; mean age 29 [17-58] years) were tested for specific adhesion molecules (lectins) to discover their relationship to blood-group characteristic carbohydrates. 52 of the 55 patients (94.5%) were blood-group A or AB (average for Middle-Europeans: 48.2%). Haemagglutination and inhibition tests with the Staph. saprophyticus isolates demonstrated in all instances N-acetylgalactosamine (GalNAc) specificity of the surface lectins. These findings support the hypothesis that the carbohydrate pattern of Blood group A (terminal GalNAc) is important for the colonization of exposed organs by Staph. saprophyticus with GalNAc-specific lectins.