Prostate surgery can improve lower urinary tract symptoms (LUTS) by relieving bladder outlet obstruction (BOO). However, surgery is less effective without BOO, or if detrusor underactivity is present. Urodynamics (UDS) can identify BOO and measure detrusor activity, but evidence in clinical practice is lacking. Urodynamics for Prostate Surgery Trial: Randomised Evaluation of Assessment Methods (UPSTREAM) aimed to evaluate whether a care pathway including UDS would reduce surgery without increasing urinary symptoms. UPSTREAM is a pragmatic, noninferiority, randomised controlled trial in men with bothersome LUTS, in whom surgery was an option, in 26 hospitals in England (ISRCTN56164274). Participants were randomised (1:1) to routine care (RC) diagnostic tests, or RC plus UDS. The primary outcome was the International Prostate Symptom Score (IPSS; patient-reported outcome scale from 0 to 35 points) 18 mo after randomisation, with a noninferiority margin of 1 point. Urological surgery rates were a key secondary outcome. The primary outcome was compared between the arms using linear regression, analysed on an intention-to-treat basis. Between October 2014 and December 2016, 820 men (median age 68 yr) were randomised (393 and 427 in the RC and UDS arms, respectively). The UDS arm showed noninferiority of the mean IPSSs (UDS 12.6; RC 13.1; adjusted difference at 18 mo −0.33 95% confidence interval {CI} −1.47, +0.80). In the UDS arm, 153/408 (38%) received surgery compared with 138/384 (36%) in the RC arm (adjusted odds ratio 1.05; 95% CI 0.77, 1.43). A total of 428 adverse events (UDS 234; RC 194) were recorded, with related events similar in both arms and 11 unrelated deaths. In this population, the UDS randomised group was noninferior to RC for the IPSS but did not reduce surgical rates. This study shows that routine use of UDS in the evaluation of uncomplicated LUTS has a limited role and should be used selectively. For men with uncomplicated lower urinary tract symptoms, symptom improvements after treatment and the number of operations performed are similar, irrespective of whether or not urodynamic tests are conducted in addition to routine tests. Accordingly, routine use of urodynamics has a limited role in this population group. The inclusion of urodynamics (UDS) in the diagnostic tests for male lower urinary tract symptoms (LUTS) resulted in a noninferior symptom outcome (International Prostate Symptom Score) to routine care, 18 mo after randomisation. However, there was no reduction in the rates of surgery for treating bladder outlet obstruction. Accordingly, the findings show that routine use of UDS in the evaluation of uncomplicated LUTS has a limited role and should be used selectively.