Urban focus of schistosomiasis in an urban area of South-eastern, Brazil. An active, urban focus of schistosomiasis in Belo Horizonte, MG, Brazil is described. It is located in the "Julien Rien" Park, a leisure area of 48,500 m2 created by the local administration in 1980 on the south side of city. Snail captures were made over 10 years (1983-1992) resulting in the collection of 3,361 Biomphalaria glabrata, ranging from 6.4 to 12.8 mm in diameter (mean = 9.3); 23 (0.7%) of these were found to be infected with Schistosoma mansoni. The finding of S. mansoni intermediate hosts in urban areas (ponds, small artificial lakes, etc) may be related to the introduction of fish and ornamental aquatic plants coming from specialized shops or areas in which they occur. It is suggested that the introduction of fish aquatic plants into urban water collections without a quarantine period should be avoided, as a prophylactic measure.