In the context of multiple myeloma (MM), early use of the immunomodulatory drug lenalidomide has led to an increased population of patients with lenalidomide-refractory MM in early-line settings, but their outcomes are not well characterized. Herein, we report treatment patterns, survival outcomes, prognostic variables, and attrition rates for patients with proteasome inhibitor-exposed, lenalidomide-refractory MM, treated with 1 to 3 prior lines of therapy (LOT). From 12 767 patients with MM in the Flatiron Health database between January 2016 and April 2022, 1455 met the inclusion criteria. The most common subsequent treatments were triplet combinations (41.6% of patients); daratumumab/pomalidomide/dexamethasone was the most common treatment regimen (13.2%). Median real-world progression-free survival (RW-PFS) and overall survival (OS) were 6.5 months and 44.4 months, respectively. RW-PFS was similar in patients with 1, 2, or 3 prior LOT. International Staging System stage III, Eastern Cooperative Oncology Group performance status of 1, hemoglobin <12 g/dL, high-risk cytogenetics, and refractoriness to anti-CD38 antibody at baseline were associated with worse RW-PFS and OS. Outcomes remained similar for patients who received National Comprehensive Cancer Network-preferred treatments and those who received treatments after 2020. In 561 patients with 1 prior LOT at inclusion, the cumulative attrition rate from LOT 2 to 5 was 85%, which included 25% patients who died and 60% with no further treatment. Patients with lenalidomide-refractory MM who have received 1 to 3 prior LOT have poor outcomes and progress rapidly through available therapies, highlighting the need for more effective treatments early in the disease course, before patients are lost to attrition.