Background: There is uncertainty about the comparative safety and effi cacy of the fi xed-dose-combination tablets tenofovir 300mg+emtricitabine 200mg (TDF/FTC); and abacavir 600mg+lamivudine 300mg (ABC/3TC). Methods: We used random effects meta-analysis to compare 96 week data for ABC/3TC and TDF/FTC randomised arms from the BICOMBO (n=333) and STEAL (n=357) treatment experienced and virologically suppressed switch studies. Endpoints included: virological failure (VF, repeat plasma HIV RNA >400 copies/mL); mean change to week 96 in CD4 and metabolic parameters; proportion with serious non-AIDS events (SNAEs, retrospectively collected in BICOMBO). We used exact statistics for relative difference in proportions (RD), and ANOVA for differences between means. Difference was for ABC/3TC minus TDF/FTC. Results: There was no signifi cant difference between arms in VF (RD% 0.7 95%CI -3.4, 4.8). Change from baseline in CD4 was of marginal signifi cance (ITT 0.16 cells/mL 95%CI 0.0, 0.32). Mean change in HDL, LDL, total cholesterol triglycerides were signifi cantly greater in the ABC/3TC arm (p <0.01 for all), there was no difference in total cholesterol:HDL ratio (0.11 95%CI -0.16, 0.29). There was a greater proportion of SNAEs in the ABC/3TC arm (relative difference 3.8%, 95%CI 0.1, 7.6) primarily arising from the STEAL study. Conclusions: In a switch study setting ABC/3TC based therapy was virologically non-inferior over 96 weeks to TDF/FTC based therapy. Lipid markers were generally elevated in the ABC/3TC arm.