Five types of space maintainers were placed in 196 children participating in an extensive dental care program during a four-year study. Children with space maintainers were examined at six-month intervals. During the study, some sort of difficulty was encountered with 43% of the appliances inserted. The most common problem encountered was lost or missing appliances. Sixteen appliances had broken arch wires or loop wires; only ten broken bands were noted. Anther problem was distortion of arch wires. Suggestions are made for possible modifications in the space maintainers to reduce the incidence of problems.