BACKGROUND Tenofovir disoproxil fumarate (TDF), a key component in many human immunodeficiency virus (HIV) treatment regimens, is associated with increased renal and bone toxicities. The contributions of such toxicities to treatment costs, as well as the relative differences in treatment costs for various TDF/emtricitabine (FTC) regimens, remains unexplored. OBJECTIVE To estimate and compare mean overall and renal- and bone-specific costs, including total, inpatient, outpatient, and pharmacy costs in patients treated with TDF/FTC+efavirenz (EFV) compared with several non-EFV-containing TDF/FTC regimens. METHODS We conducted a national cohort study of treatment-naive HIV-infected U.S. veterans who initiated treatment from 2003 to 2015 with TDF/FTC in combination with EFV, elvitegravir/cobicistat, rilpivirine, or ritonavir-boosted protease inhibitors (atazanavir, darunavir, or lopinavir). Outcomes of interest were quarterly total, inpatient, outpatient, and pharmacy costs using data from the Veterans Health Administration (VHA) electronic medical record and Managerial Cost Accounting System (an activity-based accounting system that allocates VHA expenditures to patient encounters). We controlled for measured confounders using inverse probability of treatment (IPT) weights and assessed differences using standardized mean differences (SMDs). For comparisons where SMDs exceeded 0.1 after IPT weighting, we used the more conservative matching weights in sensitivity analyses. For hypothesis testing, we compared IPT-adjusted differences in quarterly costs between treatment groups using Mann-Whitney U-tests and generalized estimating equation (GEE) regression models. RESULTS Of 33,048 HIV-positive veterans, 7,222 met eligibility criteria, including 4,172 TDF/FTC + EFV recipients; mean (SD) age of the cohort was 50.0 (10.0) years; 96.7% were male; 60.1% were black; and 30.1% were white. Quarterly periods of exposure to EFV-containing regimens were 22,499 and of exposure to non-EFV-containing regimens were 11,633. After IPT weighting, absolute SMDs were < 0.1 except for a few covariates in the rilpivirine comparison. The per-patient adjusted mean total quarterly costs were $7,145 for EFV versus $8,726 for non-EFV (P < 0.001; Mann-Whitney U-test) and the per-patient adjusted mean difference in total quarterly costs was $1,419 lower for EFV versus all non-EFV combined (P < 0.001; GEE model). Corresponding values for outpatient costs ($2,656 vs. $2,942; P < 0.001; difference, -$254; P = 0.001), inpatient costs ($2,009 vs. $2,614; P < 0.001), radiology costs ($213 vs. $276; P < 0.001), and pharmacy costs ($2,480 vs. $3,170; P < 0.001; difference, -$600; P < 0.001) were all lower for EFV versus all non-EFV combined. Findings based on matching weights were qualitatively similar. Contributions of renal and bone costs to the total costs of treatment were very small, ranging between $52 and $94 per patient per quarter for renal outcomes and between $6 and $114 for bone outcomes. CONCLUSIONS Among 7,222 HIV-treated veterans over an average follow-up of 1.2 years per patient, those patients receiving TDF/FTC + EFV had lower overall health care costs compared with those receiving non-EFV regimens. BACKGROUND This study was funded by Bristol-Myers Squibb. Nelson, Ma, Crook, Knippenberg, Nyman, and LaFleur are employees of the University of Utah, which received a grant from Bristol-Myers Squibb to conduct this study. Nyman also discloses honoraria for consulting from Otsuka and for writing a book chapter from Fresenius. La Fleur reports advisory board and consulting fees from Bristol-Myers Squibb outside of this study. Paul and Esker are employees of, and own stock in, Bristol-Myers Squibb.