Objective: Autism is more prevalent among persons with Restrictive type eating disorders (R-ED) compared to the general population and is associated with poorer outcomes across treatment modalities. Knowledge is sparse with regard to whether poorer outcomes are also associated with Family-based treatment (FBT), which is recommended as the first choice of treatment for young persons (YPs) with R-ED. This case series compares outcome between groups with and without autism in a large consecutive series of YPs with R-ED treated with FBT. Method: In an earlier described consecutive series of 157 YPs with R-ED treated with FBT, we compared the outcomes of the subgroup with (N = 16) and without (N = 141) comorbid autism. Primary ICD-10 diagnoses were typical (50.0) or atypical anorexia nervosa (AN) (F50.1), the latter implying a condition as typical AN but with a failure to meet one of the diagnostic criteria. Autism diagnoses were clinically assigned. The outcomes were receiving intensified care, weight normalisation and overall successful treatment. Results: 10.2% (N = 16) of the sample had autism. 2.5% (N = 4) had autism diagnosed prior to the Eating Disorder (ED), and an additional 7.7% (N = 12) were diagnosed with autism during ED treatment. Significantly more YPs with autism (50%, N = 8) compared with YPs without autism (16%, N = 23) received intensified care (day programme or inpatient treatment) during their treatment. No significant difference between groups regarding neither weight normalisation nor successful ending of the treatment were found. Conclusion: This small sample of YPs with autism suggests that comparable proportions of YPs with and without autism may restore normal weight and end the treatment successfully within 12 months. However, more YPs with comorbid autism needed more intensive treatment, indicating that outpatient treatment delivery may not be sufficient to bring about desired change in this patient group. Findings need confirmation in a larger sample with a systematic screening for autism.