Formerly the surgical fevers were all grouped together, and a certain amount of febrile disturbance was looked for after any injury. But with the introduction of antiseptic methods and the healing of wounds by primary union, with absence of all septic phenomena, and the use of the clinical thermometer, it is noted that there is a certain rise of temperature more or less quickly after an operation or reception of a wound, with fever of mild grade, persisting for several hours or two or three days, and with other accompaniments. This phenomenon has been carefully studied, and so separated from the septic fevers as to deserve a distinct recognition under the names above given, of which the most common in this country is _surgical fever_. As long as this fever is free from indications of septic character it is without significance and needs only symptomatic treatment. It begins usually within the first twenty-four or thirty-six hours, after which the temperature may rise, progressively or with a morning remission, to a height of 102° or possibly 103°. In children we are more likely to get extremes in this regard than in healthy adults. It will be followed by some disturbance of alimentary function, glazing or drying of the tongue, deficiency in urinary secretion, and subside generally spontaneously--invariably so if cathartics, diuretics, cool sponge baths, etc., are used. It is usually due to the retention of blood clot, ligatures, etc., or tissues which have been ligated and whose stumps remain; in all instances there is some foreign material to be removed. This means unusual phagocytic activity, perhaps temporary leukocytosis, with active metamorphosis of clot and other material, of all of which the elevated temperature is an accompaniment and expression. It is not unlikely that the antiseptic materials used may sometimes occasion this pyrexia. Iodoform and carbolic acid are among the drugs in common use which are known to be irritating and capable of producing toxic symptoms. Often after the use of the latter the urine will be discolored and will furnish the clue to the fever. In young children particularly, and not infrequently in adults, mental disturbance, even active delirium, may characterize the case. This is not always to be explained by cerebral anemia due to loss of blood during the operation or accident, but is probably due to drug toxemia or to intoxication from materials furnished by the altered tissues. _Surgical fever of strict type may merge into a more or less continuous fever as the result of intestinal toxemia_ permitted by failure to evacuate the bowels, and this _intestinal toxemia may be a predisposing cause of genuine septic infection_. Consequently a surgical fever which does not disappear within two days is to be viewed with suspicion, especially if it does not subside after the administration of cathartics.