The knowledge, attitude and practice of mothers toward childhood immunization was surveyed in 2 neighborhoods in greater Bombay, India. The areas were a slum of 75,000 called Malavani, and a nearby area called Kharodi. Measles and triple (DPT or DPV) vaccines were available at local health centers, 1.5 km away at the most; oral polio vaccines were given by field workers to the Malavani community to children in their homes, but only in the center for those in Kharodi. BCG tuberculosis vaccinations were available to all, but from a center 5 km away. Malavani mothers had significantly better knowledge of triple and measles vaccines, but knowledge about BCG was similar in the 2 groups. Slightly more women from Kharodi expressed negative attitudes toward immunization. Coverage of children, established from clinic records, was significantly better in the Malavani area: 91% vs. 58% for polio; 71% vs 61% for BCG (n.s.); 85% vs. 55% for triple vaccine; and 21% vs 1% for measles. Evidently, visitation by field teams with polio vaccinations affected mothers' knowledge and practice for other immunizations available only at the center.