To evaluate guidelines for outpatient treatment of acute pelvic inflammatory disease recommended by the Center for Disease Control we studied 197 afflicted women. The women were treated either with tetracycline or with procaine penicillin and ampicillin, and 92 per cent were subsequently seen at least once to assess efficacy of clinical and microbiologic treatment. Neisseria gonorrhoeae was isolated from the lower genital tract in 68 per cent of these women, and although they had a quicker symptomatic response than those with nongonococcal infection (P<0.01), the two regimens were equally effective in producing clinical cure. However, subsequent identification of a pelvic abscess was 10 times more common in women from whom N. gonorrhoeae was not isolated. Therapy for pelvic inflammatory disease must be empirical since it is impossible to distinguish clinically between gonococcal and nongonococcal infection, and our data indicate that both regimens recommended by the Center for Disease Control are effective. (N Engl J Med 296:1380–1383, 1977) Acute pelvic inflammatory disease remains a frequent source of morbidity in sexually active women and may result in sterility or chronic pelvic pain or both.1 In 1974 the Venereal Disease Control Advisory Committee of the Center for Disease Control2 recommended two regimens for outpatient treatment of acute salpingitis, using either tetracycline or a combination of procaine penicillin and ampicillin. These regimens are still currently recommended by the United States Public Health Service. Although organisms other than Neisseria gonorrhoeae may cause acute pelvic infection,345678 it is difficult initially to distinguish gonococcal from nongonococcal infection clinically. Since the diagnosis of acute pelvic. © 1977, Massachusetts Medical Society. All rights reserved.