Human urinary schistosomiasis transmission foci and period were investigated in an endemic town in Ijebu North, Southwest Nigeria. Three important streams (Areru, Eri-Oru and Ojupon) were sampled using long-handled scoop and a pair of tongs, between September 2002 and October 2003. Out of the 3500 freshwater snails collected, six species were identified which are Lanistes libycus (46.7%), Potadoma moerchii (31.4%), Melanoides tuberculata (1.5%), Bulinus globosus (18.2%), B.forskalii (0.2%) and Afrogyrus coretus (2.1%). 611 (96.1%) of the B.globosus recorded were from Eri-Oru and Areru streams 588 (96.2%) of the B.globosus from these two streams were recorded during little or no rainfall period when the snail infection rate range was 2.3 to 21.0%. Artificial cercarial infection of laboratory mice yielded terminally- spined eggs characteristic of Schistosoma haematobium. 16.2% and 5.0% of A. coretus collected from Eri-Oru in January and March 2003 respectively, shed cercariae which were not furcocercous. The results are discussed in relation to the nutritional significances of L. libycus and P.moerchii, findings from preliminary study and rainfall pattern in the study area. The study showed that human urinary schistosomiasis transmission occurred mainly in the dry season and that Eri-Oru and Areru streams were the main transmission foci.