In order to determine the prevalence of tic disorders in children with severe school problems requiring a residential facility and comparison groups of children in regular day schools, we performed direct clinical examinations for the presence of tics and Gilles de la Tourette's syndrome (GTS) in 20 children from a residential school for emotional and behavioral difficulties (EBD); 25 children from a residential school for learning disabilities; 17 "problem" children (PC) (identified by teachers as having academic or behaviour problems) and 19 normal children (NC) selected at random (using random numbers) from a regular school. Of the EBD students, 65% were judged to have definite tics as compared with 24% of students with learning difficulties (P < 0.05), 6% of PC (P < 0.003) and none of the NC (P < 0.0006) group. Most of the affected students met diagnostic criteria for GTS. Our findings suggest that GTS is commonly associated with the need for special education and that this association is particularly robust for children with severe school problems. In these children, the presence of tics may be an indicator of an underlying dysfunction of neurological development.