A survey has been carried out for the presence of Yersinia enterocolitica (Y.e.) in horticultural products. 100 samples of these vegetables have been examined among the families of Compositae (lettuce, prickly lettuce, cabbage lettuce, common chicory, artichoke), Umbrelliferae (curly parsley, carrot, celery, fennel), Cruciferae (garden cabbage, red radish), Liliaceae (onion), and Solanaceae (tomato). 12 strains have been recorded in carrots (serotype 0:6.30), 1 strain in curly parsley (0:4.32), 3 in celery (0:7.8 and 0:6.30), and 1 in red radish (NAG). 0:6.30--the most commonly serotype found in the horticultural products--can be of special significance in human pathology, since the reference strain (IP 102) has been first isolated from man; besides, 0:6.30 has been recovered from four cases of human infection, and represents the most frequently isolated serotype from humans in Canada, together with 0:3, 0:5.27 and 0:9. According to other Authors, in can be assumed that "environmental" strains of Y.e. may also acquire virulence and cause infection in man. Moreover, a high number of environmental biotypes in foods may mask the presence and recovery of such strains involved in human pathology.