We examined the impact of muscle relaxation on surgical conditions and patients' postoperative outcome during elective laparoscopic cholecystectomy under balanced anaesthesia.After approval and consent, 57 anaesthetized patients were randomly assigned to group no neuromuscular blockade (No NMB) and deep neuromuscular blockade (Deep NMB), i.e. no twitch response to train-of-four nerve stimulation. Laparoscopic cholecystectomy was performed using the 4-trocar technique with a CO2-pneumoperitoneum. Surgical conditions were assessed using a Visual Analogue Scale. Movement of diaphragm or abdominal muscles, inadequate visibility, or breathing and coughing against the ventilator were documented as events reflecting inadequate muscle relaxation. Independently, surgeons could request 0.3 mg/kg rocuronium to improve surgical conditions. Workflow variables were obtained as a surrogate of surgical conditions. Data are presented as mean (95 % confidence interval). The trial is registered at ClinicalTrials.gov (NCT00895778).While in 12 of 25 patients of group "No NMB" one or more adverse events impaired the surgical procedure (p< 0.001), only 1 of 25 patients of group "Deep NMB" showed an adverse event. Deep NMB resulted in an absolute risk reduction of 0.44 (0.23-0.65) and a number needed to treat of 2.3 (1.5-4.4), respectively. Surgeons requested 0.3 mg/kg rocuronium in 10 of 25 cases (40 %) of group "No NMB" only. This dose significantly improved surgical conditions by an average 62 of 100 possible points. All further variables did not differ between groups.Deep NMB ameliorates surgical conditions for laparoscopic cholecystectomy by improved visibility and reduction of involuntary movements.