The incidence of posterior crossbite in the primary dentition has been reported as 7-17%. The crossbite usually results from bilateral maxillary constriction and is commonly associated with an occlusion guided lateral deviation of the mandible upon closing. Correction of the functional posterior crossbite in the primary dentition is indicated to establish a stable occlusion and avoid possible deleterious effects on the developing temporomandibular joint. Treatment in the primary dentition results in the eruption of the first permanent molars in normal transverse relationship in 84% of the cases. The diagnosis and management of two cases is presented.