Background: The goal of the current study was to determine if the Dementia Rating Scale-2 (DRS-2) is an appropriate tool for evaluating cognitive abilities in adults with Prader-Willi syndrome (PWS). The DRS-2 is a screening measure previously utilised in low-functioning populations with and without dementia, including individuals with intellectual disability. Method: Thirteen adults with PWS between 21 and 59 years old were administered the DRS-2. Results: Participants demonstrated impairment on all 5 subscales, with the largest impairments observed on the Initiation/Perseveration and Construction subscales. No significant floor or ceiling effects were observed. No correlations were observed between age and any subscale score. Conclusion: The DRS-2 may be a valid assessment tool for capturing the full spectrum of cognitive functioning in adults with PWS. The largest impairments were observed on items requiring verbal and motor fluency and visuo-spatial processing. Future directions for the use of the DRS-2 in this population are discussed.