The relationship between the forces applied during laryngoscopy and cardiovascular changes were studied in patients undergoing laryngoscopy with or without intubation. This enabled us to differentiate between the cardiovascular effects of laryngoscopy and the effects of tracheal intubation. The forces applied during laryngoscopy were only weakly related to the cardiovascular changes, whereas tracheal intubation had a major influence. The many difficulties encountered in interpreting results from these studies are discussed. It is concluded that tracheal intubation causes more cardiovascular changes than laryngoscopy in routine uncomplicated procedures.