The objective of this study is to investigate whether parentally-reported 
gastro-intestinal (GI) symptoms are increased in a population-derived sample of 
children with autism spectrum disorders (ASD) compared to controls. Participants 
included 132 children with ASD and 81 with special educational needs (SEN) but 
no ASD, aged 10-14 years plus 82 typically developing (TD) children. Data were 
collected on GI symptoms, diet, cognitive abilities, and developmental 
histories. Nearly half (weighted rate 46.5 %) of children with ASD had at least 
one individual lifetime GI symptom compared with 21.8 % of TD children and 
29.2 % of those with SEN. Children with ASD had more past and current GI 
symptoms than TD or SEN groups although fewer current symptoms were reported in 
all groups compared with the past. The ASD group had significantly increased 
past vomiting and diarrhoea compared with the TD group and more abdominal pain 
than the SEN group. The ASD group had more current constipation (when defined as 
bowel movement less than three times per week) and soiling than either the TD or 
SEN groups. No association was found between GI symptoms and intellectual 
ability, ASD severity, ASD regression or limited or faddy diet. Parents report 
more GI symptoms in children with ASD than children with either SEN or TD 
children but the frequency of reported symptoms is greater in the past than 
currently in all groups.