Background: At present there is a substantial uncertainty regarding the extent and nature of autism spectrum disorder (ASD) and bipolar affective disorder (BPAD) co-occurrence due to disparate findings in previous studies. This paper aimed to find and review original studies on co-occurrence rates of ASD with BPAD, assess them, synthesize the findings in a systematic way, present an overview and make recommendations for future research. Methods: Systematic literature searches were performed using several databases. Selected articles had to describe an original study that provided prevalence and/or incidence analysis on ASD co-occurring together with BPAD. Results and Conclusion: A significant minority of patients (7%) with ASD suffers from BPAD. An accurate detection of co-occurring ASD and BPAD can lead to a more targeted treatment and improve the patients' functioning and quality of life.