The aim of our study was to compare leakage pressure, ease and time of insertion of the i-gel and the LMA-Unique laryngeal mask airway in patients with mild to moderate obesity during elective short-term surgery. In this prospective, randomised crossover trial, we included patients with a body mass index (BMI) >25 and <35 kg.m(-2) , and , age >18 years, undergoing elective surgery in the supine position with an expected duration of surgery <2 h. Leakage pressures, insertion difficulty, time and number of insertion attempts were evaluated. We included 50 patients consisting of 29 mildly (BMI>25 and < 30 kg.mg(-2) ) and 21 moderately (BMI>30 and < 35 kg.mg(-2) ) obese patients. Mean (SD) leakage pressures were 23.7 (9.2) cmH₂O (i-gel) and 17.4 (7.0) cmH₂O (LMA-Unique) (p<0.01). Subgroup analyses showed leakage pressures of 22.2 (9.4) cmH₂O (i-gel) and 17.5 (7.5) cmH₂O (LMA-Unique) (p=0.013) in the mild subgroup, and 25.7 (8.6) cmH₂O (i-gel) and 17.0 (6.2) cmH₂O (LMA-Unique) (p<0.01), in the moderate subgroup. Insertion of the i-gel was associated with significantly higher leakage pressures compared with the LMA-Unique in mildly and moderately obese patients.