Background: The sustained effects of onabotulinumtoxinA in patients with cervical dystonia (CD) who were naïve or non-naïve to botulinum toxin at enrollment in CD PROBE (CD Patient Registry for Observation of BOTOX® Efficacy) were evaluated. Methods: Patients were included if they completed all three treatment cycles and had accompanying data in this prospective, observational study. Assessments included CD severity, Cervical Dystonia Impact Profile (CDIP-58), Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), treatment interval, total dose, and adverse events (AEs). Results: Changes in severity following each onabotulinumtoxinA treatment were generally similar between naïve (n=212) and non-naïve (n=138) patients. Severity scores were maintained or improved in most patients with mild/moderate symptoms, while 30.0-66.7% with the highest severity scores shifted to a lower score across treatments. Sustained improvements were seen in all CDIP-58 subscales and TWSTRS total scores irrespective of baseline CD severity and toxin status. The median time interval between injections was similar in naïve (93.0–98.0 days) and non-naïve patients (96.0–97.0 days); doses tended to be lower in naïve patients. The most common AEs (dysphagia, muscular weakness) were similar. Conclusions: CD severity was attenuated by repeat onabotulinumtoxinA treatments at consistent intervals regardless of prior botulinum toxin exposure. Treatments were well tolerated.