Objective This study aimed to investigate the effects of neuromuscular blocking drugs on the viability of human umbilical vein endothelial cells (HUVECs) and to investigate whether they cause vascular complications due to cell proliferation. Methods HUVECs were cultivated with 5% CO(2)at 37 degrees C in a predefined supplemented medium over 7 days until confluence of cell monolayers. Assays were conducted during the exponential growth phase. Suxamethonium chloride, vecuronium bromide, atracurium besylate, and rocuronium bromide were used at concentrations of 10(-5), 10(-6), and 10(-7)M in proliferation assays in which cells were incubated with these drugs for 24, 48, and 72 hours. All experiments were performed in four replicates. Results The neuromuscular blocking drugs used had comparable effects on the survivability of HUVECs. Overall, no significant difference was observed in the survivability of HUVECs in a dose-dependent manner after exposure to the study drugs. However, some significant differences in the viability of HUVECs were found among the different measurement times. Conclusions The findings of the current study support the safety of the studied neuromuscular blocking drugs in clinically relevant concentrations regarding their effects on endothelial cell proliferation.