Background: In the US, Human Papillomavirus (HPV) vaccination coverage is low, particularly in adolescents aged 13-15 years with respect to the Healthy People 2020 goal of 80%. There has been variability in the definition of measuring vaccination coverage in published studies. We examined complete HPV vaccination coverage in a population of privately insured individuals in the US. Methods: This retrospective study used IBM MarketScan Commercial Database, years 2006 to 2018. Inclusion criteria were ages 9 to 45 years and continuous enrollment from age 9 years or from 2006. Complete HPV vaccination coverage was defined as receipt of 2 doses (age 9-15 years) or 3 doses (age 16-45 years) within 12 months and stratified by year, demographics, and US region. Mean vaccination costs per dose were summarized by vaccine brand and health plan type. Results: The table summarizes complete HPV vaccination coverage by selected age groups for 2006 (n=12,221,938), 2010 (n=4,692,633), 2014 (n=2,808,132), and 2018 (n=1,662,148). From 2017 to 2018, the percentage of members who received HPV vaccine increased; for females ages 13-15 by 1% and 16-17 by 5% while for males ages 13-15 by 6% and 16-17 by 15%. In 2018, by region, the highest coverage was in females aged 18-26 at 53% and males aged 16-17 at 43% in the Northeast, and mean cost for each brand was $120 (-6% from 2017), $165 (-3%) and $220 (+5%) for Cervarix (n=151), Gardasil (n=8,201) and Gardasil 9 (n=139,356), respectively. The rate of utilization of Gardasil 9 increased from 33% (2015) to 94% (2018) of all vaccines. The lowest mean HPV vaccine cost by health plan type and brand was with Point-of-Service (POS) and Cervarix at $106, and the highest was with POS with Capitation and Gardasil 9 at $243. Conclusions: In a commercially insured US population, complete HPV vaccination coverage was lower than the Healthy People 2020 goal, but increased over time. Coverage varied according to health plan type and by region. In 2018, Gardasil 9 had the highest mean cost but was the most utilized vaccine, which may be related to broader coverage of HPV types. This study was limited by the transient nature of member enrollment and complexity of measuring complete vaccination coverage. These results should inform policy makers and practicing clinicians about the gap in vaccination coverage.