Pancreatic cancer is a major cause of cancer-associated mortality, with a dismal overall prognosis that has remained almost unchanged for many decades. Pancreatic cancer has few prevalent genetic mutations. Available data on dMMR pancreatic cancer is limited and heterogeneous with regard to its prevalence and prognostic implications. Discordant results are mainly due to differences in detection methods and sample sizes. Interest in dMMR is growing since initial reports on immune checkpoint inhibition therapy for pancreatic cancer has shown it to be effective, generating impressive and durable responses. However, it has been accompanied by several questions regarding the appropriate screening, detection tools, patient selection, timing and modality of testing. Herein, we provide an extensive literature review and outline recommendations for testing.