Univariate analyses showed that difficult intubation was associated with neck circumference, males, BMI more than 50  kg  m(-2), American Society of Anesthesiologists (ASA) status and waist circumference, and difficult mask ventilation with neck circumference, males, BMI more than 50  kg  m(-2) and thyromental distance. Multiple logistic regression analysis showed that neck circumference more than 42  cm (P = 0.044) and BMI more than 50  kg  m(-2) (P = 0.017) were independent predictors of difficult intubation. Male sex (P = 0.004) and BMI more than 50  kg  m(-2) (P = 0.031) were independent predictors of difficult mask ventilation.