Shortly after the publication of our literature review on gluten-free and casein-free (GFCF) diets in the treatment of autism spectrum disorders (ASD; Mulloy et al., 2010), Whiteley et al. (2010) published the results of experimental evaluation of a GFCF diet. To update our previous literature review, we herein provide an analysis of the Whiteley et al.'s study. The study was well designed, but also contains substantial weaknesses that suggest the need for caution in interpreting the findings reported by Whiteley and colleagues. In conclusion, we maintain our previous position that GFCF diets are not effective in treatment of core symptoms of ASD and should only be implemented in the event a child with ASD experiences acute behavioral changes, seemingly associated with changes in diet, and/or medical professionals confirm through testing the child has allergies or food intolerances to gluten and/or casein.