PIP: This paper describes a clinical test that has been found effective in diagnosing pregnancy in the first 10 days after a missed period. The patient is given 125 mg of progesterone im in 2.5 ml of oil, then 4 tablets of 2.5 mg each of conjugated equine estrogens (Premarin, Amnestrogen, or Conestion) are given at bedtime with the same dose repeated the next morning. If no bleeding occurs by Day 8 of treatment, pregnancy is diagnosed. The test was used in 168 women with previously normal menstrual cycles. In 52 pregnancy was present and diagnosed. In the only other false negative report an abortion occurred 2 days after the injection. The test did not affect the course of established intrauterine pregnancies. No severe reactions were seen. A total of 5 false positive reports were given. Of these 2 were taking large doses of phenothiazine tranquilizers, 2 had enlarged ovaries, and 1 had pelvic inflammatory disease. Progesterone alone will not always produce withdrawal bleeding. The combination with estrogen may be needed. This test is considered accurate within the first 10 days of pregnancy in 96% of cases. It has several advantages over other methods.