Structured Abstract Authors – Heikkinen T, Alvesalo L, Tienari J Objectives – To explore deciduous tooth crown dimensions in strabismic children and the relationship between the type of strabismus and tooth crown mesio‐distal (M‐D) and labio‐lingual (L‐L) size asymmetries. Material – Dental casts at mixed dentition of 2159 Collaborative Perinatal Study black and white children were measured, 123 of them strabismic at 1 year of age, age ranging from 6 to 12 years. Methods– Directional and fluctuating asymmetries in antimeric teeth were explored in various types of strabismus having unilateral, bilateral or alternating expression. ANOVA and T‐square test were used for size comparisons and calculated asymmetries were explored by comparing the variances and Pearson correlations. Results – Strabismus was associated with significant M‐D size increase of deciduous maxillary canines in black boys and white girls, black girls had size reduction in their mandibular canine, but white boys were unaffected. Right side size dominance was found in the strabismic children in the lower second deciduous molar M‐D dimensions and in the children with alternating strabismus in their upper deciduous canine M‐D dimensions. Children with unilateral strabismus had random fluctuating dental asymmetry in their upper deciduous second molar L‐L dimensions when compared with healthy normals. Higher left‐right correlations were found in lower second deciduous molar dimensions in strabismic girls when compared with that in controls and in strabismic boys, suggesting better developmental canalization in female. Conclusions – Asymmetries in the head area, such as promoted here in strabismic children, may have associations with asymmetries in the dentition, focusing the embryonal origins and timing of developmental processes.