Each subject received a dose of 20 units incobotulinumtoxinA (Xeomin) for i.m. injection on Visit 1 (Day 0 of Cycle 1). Re-injections with 20 U NT 201 could be performed on Day 0 of a subsequent cycle for up to 8 cycles (one cycle ≥ 85 days). Intervals between treatments were at least three months or 12 weeks, i.e., ≥ 85 days. For a new treatment cycle to start, the subject had to request a re-injection. The investigator then had to assess if the glabellar frown lines had relapsed to 'moderate' or 'severe'. In this case, a new injection could be administered. The treatment duration per subject was 24 months and up to eight cycles for subjects enrolled from studies MRZ 60201-0520/1 and MRZ 60201-0527/1 and 6 months and up to two cycles for subjects enrolled from studies MRZ 60201-0724/1 and MRZ 60201-0741/1, respectively. Subjects enrolled from studies MRZ 60201-0520/1 and MRZ 60201-0527/1 participated at least one year in the study whereas subjects enrolled from studies MRZ 60201-0724/1 and MRZ 60201-0741/1 participated for six months and up to two cycles.