To the Editor .—In the December issue of theJournal(126:779, 1973), McReynolds and Roy emphasize the early diagnosis of Rocky Mountain spotted fever so that antibiotic therapy may be instituted prior to the onset of serious, life-threatening complications. I would like to stress, as do others, 1 that specific antibiotic therapy may have to be begun before the development of any rash, especially if the patient lives (or has traveled recently in) an endemic area and gives a history of tick bites. Such tetracycline therapy, in a seriously ill individual, may fortuitously prove beneficial for other tick-borne diseases such as tularemia. 2 However, in the case of some tick-borne diseases (Table 1,3-10 ), this antibiotic therapy would be of no benefit at all.