Mastisol is a waterproof, clear liquid adhesive that has largely replaced tincture of benzoin as part of occlusive dressings (for nerve block catheters, IVs, arterial and central lines) as it is reported to have a significantly lower risk for skin irritation (1). As such, Mastisol has essentially become a standard of care for skin fixation and dressing of numerous catheter types. Papers in both the adult and pediatric regional anesthesia literature cite the use of Mastisol as a routine component of catheter fixation and dressing as well (2-4). However, there is little data in the literature evaluating the efficaciousness of Mastisol insofar as reducing catheter leakage or dislodgement and hence justifying its continued use as a part of catheter dressings. One study on healthy adults demonstrated differential forces required to dislodge a taped IV catheter with or without Mastisol (64 ± 1 vs. 46 ± 2 Newtons) however there is no data about catheter dislodgement rates over time in a clinical setting (5). One case report in the pediatric literature proposes a theoretical benefit of Mastisol use insofar as preventing regional anesthesia catheter dislodgement, but it too provides no clinical data (6).