Traditional vegetables in Tanzania have been underutilized by farmers and neglected by research and development programmes. In the framework of the project 'Promotion of Neglected Indigenous Vegetable Crops for Nutritional Health in Eastern and Southern Africa' led by the World Vegetable Center (AVRDC) and partners, focus group meetings were conducted in 10-12 villages in each of four districts of north-east Tanzania, which differed in ethnicity as well as in altitude, climate and soil conditions. Farmers named 10 -34 different traditional vegetables per village, summing up to an overall of 102 in all four districts, about half of which were only identified by local names. The number of wild traditional vegetables used was always greater than the number of cultivated traditional types, with ratios of wild to cultivated vegetables ranging from 11:9 in an urban highland district to 59:11 in a rural coastal district. Some wild traditional vegetables were found to be threatened with genetic erosion due to changes in land use and eating habits. The degree of urbanization and the availability of infrastructure contributed more strongly to genetic erosion as compared to climatic conditions. Farmers' training encouraged exotic vegetable cultivation and reduced traditional vegetable diversity. At the same time, indigenous knowledge on how and where to collect, cultivate and prepare traditional vegetables was disappearing.