Prior studies estimate that >40% of long-stay nursing home (NH) residents experience persistent pain, with 20% of residents in pain receiving no analgesics. Strengthened NH surveyor guidance and improved pain measures on the Minimum Data Set (MDS) 3.0 were introduced in March 2009 and October 2010, respectively. This study aimed to provide estimates after these important initiatives of: 1) prevalence and correlates of persistent pain; and 2) prevalence and correlates of untreated or undertreated persistent pain. We identified 1,387,405 long-stay residents in United States NHs between 2011-2012 with 2 MDS assessments 90 days apart. Pain was categorized as persistent (pain on both assessments), intermittent (pain on either assessment), or none. Pharmacologic pain management was classified as untreated pain (no scheduled or as needed medications received) or potentially undertreated (no scheduled received). Modified Poisson models adjusting for resident clustering within NHs provided adjusted prevalence ratios estimates (APR) and 95% confidence intervals (CI).The prevalence of persistent and intermittent pain was 19.5% and 19.2% respectively but varied substantially by age, gender, race/ethnicity, cognitive impairment, and cancer. Of residents in persistent pain, 6.4% and 32.0% were untreated or undertreated. Racial/ethnic minorities (non-Hispanic blacks vs. whites, APR=1.19, 95% CI: 1.13-1.25) and severely cognitively impaired residents (severe vs. no/mild APR=1.51, 95% CI: 1.44-1.57) had an increased prevalence of untreated and undertreated pain. One in five NH residents has persistent pain. Although this estimate is greatly improved, many residents may be undertreated. The disturbing disparities in untreated and undertreated pain need to be addressed.