A cross-sectional survey of the use of CAM by children was undertaken in the Duchess of Kent Children's Hospital in Hong Kong (March-December 2006). A questionnaire survey concerning the use of CAM was administered to chief caretakers (only the mothers) who accompanied children with neurodevelopmental disabilities followed up in our Neurodevelopmental paediatrics clinics. Four hundred and thirty agreed for interview of which 98 (22.8%) had Autism Spectrum Disorder (ASD). CAM was used in 40.8% for ASD and 21.4% of non-ASD (p < 0.001). We describe the profile of use of CAM in ASD in this part A paper. The three most common type of CAM use was Acupuncture (47.5%), Sensory Integration (42.5%), and Chinese Medicine (30%). About 76.9% of interviewees expected CAM to augment conventional treatment. Although 47.5% used both conventional western medicine and CAM, only 22.4% disclosed the use of CAM to Doctors. The following factors were significantly related to CAM use: father's job and mother's religion. Our frequency of CAM used in children with ASD was lower in Canada (52%) and USA (74%, 92%). The main CAM use in western culture was biological-based therapy whereas acupuncture was the most common CAM used in our locality.