e19519 Background: Few studies have assessed the relationship between adherence to prescribed therapies and patient (Pt)-reported outcomes (PRO) in Multiple Myeloma (MM). Pt-reported adherence and its association with quality of life (QoL), healthcare resource use (HRU) and functional impairment among pts on oral MM treatments were assessed. Methods: This was a cross-sectional survey of 118 US adult MM pts identified from the Light Speed Research panel, who were currently on a regimen which included an oral therapy. Pt’s experiences using the Morisky Medication Adherence Scale-4 (MMAS-4), the Work Productivity and Activity Impairment, and the Functional Assessment of Cancer Therapy (FACT)-MM were examined. Higher FACT-MM scores indicated better health-related QoL. Pts were characterized by their MMAS score; score =4 and score ≤3 (max score =4). Pts in each score grouping were summarized based on pt characteristics, treatment history, HRU and PROs. Multivariable analyses estimated the association between MMAS score group and study outcomes. Results: A total of 72 (61%) pts reported a MMAS score = 4 and 46 (39%) pts had a score ≤3. Pts with a score =4 were older (59.2 vs 50.7 years; p<0.001) and were on fewer treatments (1.42 vs 2.13; p<0.001) than with a score ≤3. No differences in race/ethnicity, marital status, income or education level were noted between the two groups. Pts with a score ≤3 had higher levels of absenteeism, impairment while at work (presenteeism), and overall work impairment in descriptive analysis, but only differences in activity impairment (56.5% vs. 39.8%; p=0.015) remained significant in the multivariable analyses. Pts with a score = 4 reported higher FACT-MM scores (106.9 vs 89.2; p<0.001) than pts with a score ≤3, a trend seen in all FACT-MM subscores. More pts with a score ≤3 also reported being overwhelmed or frustrated by having to reschedule MM appointments (64% vs. 26%; p=0.002). Conclusions: Among MM pts on oral treatments, high adherence is associated with improved QoL and a lower level of activity impairment. There may also be a relationship between frustration in managing MM related appointments and levels of adherence.