Background and objective. The use of botulinum toxin type A for treating glabellar lines is nowadays one of the most frequent nonsurgical cosmetic procedures, and upper eyelid ptosis (blepharoptosis) is one of the common minor side effects on this procedure. Through a retrospective study we present our experience and puncture technique which we consider has significantly reduced the incidence of upper eyelid ptosis secondary to the treatment of glabellar lines using one of the commercially available forms of botulinum toxin type A. Our aim is to explore whether the change in the form of infiltration of glabellar muscles has decreased the incidence of ptosis in our case series using OnabotulinumtoxinA, maintaining the same therapeutic effectiveness. Methods. Medical records of 2 consecutive series of 247 patients each where reviewed comparing the results of the treatment of glabellar lines obtained with the infiltration of the glabellar muscles with perpendicular and with parallel puncture of the lower zone of the frontal periosteum. We use OnabotulinumtoxinA in both series. Results. The perpendicular puncture procedure was associated with a ptosis incidence of 1.22%, compared to absence of ptosis with the parallel puncture. Conclusions. In our experience, parallel infiltration of OnabotulinumtoxinA for the treatment of glabellar lines reduced the incidence of ptosis without affecting the effectiveness of treatment.