ABSTRACT: The aim of this study in patients with post-stroke lower limb spasticity (PSLLS) was to evaluate the relationship between time of onabotulinumtoxinA treatment relative to stroke and efficacy outcomes. This was a phase 3, international, multicenter, randomized, 12-week, double-blind study, followed by a repeated treatment, open-label extension. Patients were aged 18-85 years with PSLLS (Modified Ashworth Scale [MAS]???3) of the ankle with the most recent stroke occurring???3 months before screening. Patients (double-blind phase) were randomized (n?=?468) to onabotulinumtoxinA 300-400 U (300 U, mandatory ankle muscles (gastrocnemius, soleus, tibialis posterior); and???100 U, optional lower limb muscles (flexor digitorum longus, flexor hallucis longus, flexor digitorum brevis, extensor hallucis, and rectus femoris]) or placebo. Primary endpoint: MAS change from baseline (average score of weeks 4 and 6). Secondary endpoints: physician-assessed Clinical Global Impression of Change (CGI) average score of weeks 4 and 6 and physician-assessed Goal Attainment Scale (GAS; active and passive, weeks 8 and 12). When stratified by time since stroke (??24 months, n?=?153;?>?24 months, n?=?315, post hoc), patients treated???24 months post-stroke experienced greater improvements from baseline versus placebo in MAS (-?0.31 vs?-?0.17), CGI (0.49 vs 0.12), and passive GAS scores (week 12, 0.37 vs 0.26). A????-?1-point improvement in active (week 12; p?=?0.04) and passive (week 8; p?=?0.02) GAS scores versus placebo was achieved by more patients treated???24 months post-stroke; in patients treated?>?24 months post-stroke, improvements were only observed in active scores (week 8; p?=?0.04). OnabotulinumtoxinA 300-400 U was well tolerated, with no new safety findings.