We predicted that teacher reported language problems are associated with low IQ, even when gender and behavior-emotional disorders are controlled for. All subjects were participants in a population based study. In stage 1, teachers completed a questionnaire containing four items pertaining to language function. A case-control sample (n= 294) was assessed using WISC-III and Kiddie-SADS-PL. A child was defined with "language problems" (LP) if s/he obtained a score indicating severe problems on at least one item. Teacher reported LP was found in 9.9% of the population sample and 20.7% of the case-control sample, with a three-fold higher risk for boys than girls. The LP group obtained significantly lower scores on all WISC-III factors compared with the non-LP group. The differences were not accounted for by the presence of behavioral-emotional disorders. When primary school teachers report LP, further assessment of the child's cognitive function is warranted.