Background: Few studies examine HRU of CLL, the most common hematologic malignancy in adults. This study describes HRU by the most common regimens among CLL patients (pts). Methods: A retrospective study using a large, national US claims database from 1/2007-10/2013 was conducted. Adult CLL pts (≥2 claims for CLL) with ≥1 claim for systemic anti-cancer therapy (SACT) were identified; first SACT claim date was the index date. Pts had to have a CLL diagnosis within 3 months (m) prior to the index date and be continuously enrolled (CE) in the health plan for 24m pre- and ≥6m post-index date. Pregnant pts and those with SACT in the pre-index period were excluded. A line of therapy (LOT) started with the first SACT; regimens included all agents received in the 1^st 60 days. LOTs ended at the earliest of, start of a new drug, ≥60-day gap in receipt of initial regimen drugs, death or CE end. All-cause HRU was examined by regimen. Results: There were 946 CLL pts identified. Mean age was 68 yrs, 63% were male and by insurance type, 41% were Medicare Advantage vs. 59% commercially insured. During the 1^st LOT, 96% and 78% of pts had ≥1 office or hospital outpatient visit with mean per patient per month (PPPM) visits of 4.3 (standard deviation, SD=2.8) and 2.2 (SD=2.8), respectively. 31% and 25% had ≥1 ER visit or inpatient stay with mean PPPM visits of 0.2 (SD=0.4) and 0.1 (SD=0.3), respectively. Mean PPPM count of inpatient stay days was 1.4 (SD=8.0). In 1^st LOT, the top 3 regimens accounted for 56% of pts: FCR: fludarabine, cyclophosphamide, rituximab (19%); R: rituximab (19%); BR: bendamustine, rituximab (18%). During the study period, 318 pts (34%) started a 2^ndLOT. The top 3 LOT2 regimens accounted for 52% of pts: R (30%); BR (14%); chlorambucil (8%). Conclusions: HRU of CLL pts varied by initial regimen received. Future studies should examine influences of regimen choice and whether regimen choice is associated with differences in outcomes.