Association of immunoglobulin isotypes with survival in the context of modern prognostic factors has not been determined. We utilized the Flatiron Health Electronic Health Record database and identified 8468 MM patients. Compared to IgG MM, patients with IgA MM were more likely to have ISS-III, anemia, and t(4;14), and light chain (LC) MM had higher renal dysfunction and t(11;14). IgA and LC MM patients have an inferior OS. The adverse prognostic impact of IgA and LC isotypes on OS persisted even after adjustment for variables impacting outcomes and likely suggests their unique biology beyond the presence of adverse prognostic factors.