Introduction: Combination therapy with an alpha blocker (AB) plus an antimuscarinic (AM) is recommended for men with moderate-to-severe mixed lower urinary tract symptoms (LUTS) when monotherapy is not effective in relieving storage symptoms. This study compared treatment persistence and adherence with an AB plus AM fixed-dose combination (FDC) vs an AB plus AM free-dose combination in men with LUTS in Spain. Methods: Retrospective study using the Spanish IQVIA Cegedim Electronic Medical Records database. Men prescribed AB plus AM combination therapy were included in an FDC or free-dose combination cohort based on their index treatment. Treatment persistence was the time from index date to first discontinuation of ≥1 of the two index drugs over 12 months. Adherence was measured using the fixed medication possession ratio (MPR). Results: Of 3114 patients identified, 999 were included (FDC, n = 790; free-dose combination, n = 209). Median (95% CI) persistence was longer in the FDC (125 [109-151] days) than in the free-dose combination (31 [31-36] days) cohort (hazard ratio [HR], 2.9; 95% CI, 2.4-3.4; P < .0001). The 12-month persistence rates were 31.1% (FDC cohort) and 8.9% (free-dose cohort). The mean (SD) fixed MPR was higher in the FDC cohort (48.8 [37.2]) compared with the free-dose cohort (23.1 [28.4]); more patients in the FDC cohort (34.2%) than in the free-dose cohort (10.