Background: Pistachio nuts may be consumed as raw nuts or as roasted nuts. However, there is limited information about protein quality of the nuts and amino acid (AA) digestibility and protein quality have not been reported. Therefore, the objective of this research was to test the hypothesis that raw and roasted pistachio nuts have digestible indispensable amino acid scores (DIAAS) and protein digestibility corrected amino acid scores (PDCAAS) that are greater than 75, thereby, qualifying them as a good source of protein. Results: The standardized ileal digestibility (SID) of all indispensable AA, except Arg and Phe, was less in roasted pistachio nuts than in raw pistachio nuts (P < 0.05). Raw pistachio nuts had a PDCAAS of 73 and roasted pistachio nuts had a PDCAAS of 81, calculated for children 2 to 5 years, and the limiting AA in the PDCAAS calculation was Thr. The DIAAS calculated for children older than 3 years, adolescents, and adults was 86 and 83 for raw and roasted pistachio nuts, respectively. The limiting AA in both raw and roasted pistachio nuts that determined the DIAAS for this age group was Lys. Conclusion: Results of this research illustrate that raw and roasted pistachio nuts can be considered a good quality protein source with DIAAS greater than 75, however, processing conditions associated with roasting may decrease the digestibility of AA in pistachio nuts. This article is protected by copyright. All rights reserved.