Methods: cross-sectional study in Nghe An province with 14.000 childrens from 12 - 72 months of age in 7 district representatives for four geographic regions including Vinh City, Dien Chau, Quynh Luu, Tan Ky, Thanh Chuong, Nghia Dan, Quy Chau. Result: Ratio of autistic children < 6 years old is: 1.57%.