Tracheal intubation under general anesthesia is common. In clinical practice, intubation may be carried out on patients in various positions, depending on the situation. Most patients are intubated in a supine position, while the lateral position is used infrequently, and prone-position intubation is rare. This report describes three patients who were intubated in the prone position. The three were undergoing elective surgery and initially received spinal anesthesia, but because the surgeries were unexpectedly prolonged, general anesthesia was required and intubation had to be carried out in the prone position. From our experience in these cases, we have found that bronchoscope-aided intubation of prone patients is quite similar to bronchoscope-aided intubation of supine patients.