There is an association between psychiatric disorders and dyslexia. In some psychiatric disorders abnormal urinary peptide patterns and peptide levels, and elevated levels of IgA antibodies to food proteins have been detected. These abnormalities are probably due to insufficient breakdown of the proteins gluten and casein. The aim of this study was to discover whether such abnormalities could be found in urine samples and serum of children with dyslexia. After screening 291 pupils in the fourth grade, 15 dyslexics and 15 controls were pairwise matched by gender, age, and cognitive level. Word decoding, spelling, and short-term memory tests were carried out, and information on handedness, immune and other disorders was obtained. Analyses of 24-h urine samples and of serum were performed. The reading abilities significantly differentiated the groups, and significant differences were found in frequency of left-handedness, immune disorders and other disorders. Three dyslexic children had elevated IgA antibodies. Two of these had positive endomycium tests, and coeliac disease was confirmed by biopsy. One had antibodies to proteins in milk. Our findings may suggest weak urinary peptide abnormalities in the dyslexic children, and they show significant differences in levels of IgA of antibodies to food proteins.