This paper reports the oral health approach of a child with Coffin-Siris syndrome. This syndrome is a multisystem congenital anomaly caused by mutations in genes of BRG-1-associated factors complex. Individuals with this syndrome have been described with hypoplasia or aplasia of the fifth digit nails or phalanges. Other features include growth deficiency, developmental and intellectual delay, and other organ-system abnormalities. Clinical examination revealed gingival hyperplasia in the upper arch, dental biofilm, and dental caries on the lower deciduous and permanent molars. Guidelines on oral hygiene and dietary habits were provided to the guardians, and tooth extraction and restoration with glass-ionomer cement were performed. This case suggests that these patients require home care and periodic dental consultations for preventive and systematic dental treatment and quality of life improvement. The patient is being monitored, and her oral condition has improved.