IN THE UNITED KINGDOM ABOUT 90 PERCENT OF SUICIDES ARE BY HANGING. OTHER FORMS OF ACCIDENTAL OR SELF-INFLICTED ASPHYXIAL DEATH ARE AMONG THE MOST COMMON EVENTS IN FORENSIC PRACTICE. STRANGLING AND SUFFOCATION ARE ALSO EXTREMELY COMMON FORMS OF MURDER. STRANGULATION CUTS OFF AIR BY MEANS OF A LIGATURE, SUCH AS A ROPE, BELT, SCARF, OR STOCKING. SMOTHERING CAN BE DIFFICULT TO DETECT BECAUSE PRESSURE MARKS MAY NOT BE FOUND IF A SOFT, THICK PILLOW IS USED. TECHNIQUES FOR DETECTING NAIL MARKS ON THE SIDE OF THE HEAD ARE GIVEN. SUFFOCATION RESULTS WHEN THE SUPPLY OF AIR IS REDUCED GRADUALLY AND IS COMMON WHEN CHILDREN PULL PLASTIC BAGS OVER THEIR HEADS. IT IS ALSO COMMON IN MENTAL HOSPITALS. CHOKING OCCURS WHEN A FOREIGN OBJECT, SUCH AS FOOD OR A SMALL OBJECT, OBSTRUCTS THE LARYNX OR TRACHEA. THROTTLING IS CONSTRICTION OF THE NECK WITH THE HANDS. CRUSH ASPHYXIA IS MOST COMMONLY SEEN IN ACCIDENTS WHEN A PIECE OF MACHINERY OR A WALL OF EARTH CAVES IN UPON A PERSON. PHOTOGRAPHS ILLUSTRATE THE DAMAGE TO THE LARYNX, TRACHEA, AND LUNGS WHICH OCCUR WITH EACH TYPE OF INJURY. THE PETECHIAL HEMORRHAGES WHICH ARE COMMON IN THE UPPER EYELID OR IN OTHER SOFT TISSUES ARE ILLUSTRATED. THE PATHOLOGIST IS WARNED THAT ASPHYXIAL DEATHS OFTEN SEEM TO BE CARDIAC ARREST. CAREFUL EXAMINATION MUST BE MADE BEFORE HASTILY ASSUMING THE DEATH WAS NATURAL. THE OBVIOUS MARKS AND INJURIES WHICH SIGNAL STRANGULATION AND THROTTLING ARE ILLUSTRATED. THE MORE SUBTLE CHANGES FOUND IN SUFFOCATION AND CHOKING ARE DETAILED AND AUTOPSY TECHNIQUES FOR REVEALING THESE CHANGES ARE DESCRIBED. A GREAT DEAL OF ATTENTION IS PAID TO DIAGNOSING ASPHIXIAL DEATH IN CHILDREN, PARTICULARLY 'SUDDEN INFANT DEATH SYNDROME.' REFERENCES ARE APPENDED. (GLR)