THE AVAILABILITY of a 19-nor progestational compound mixed with a small amount of estrogenic substance provided the opportunity to study the effect of the pseudopregnant state of the course of rheumatoid arthritis in a selected group of patients. Seventeen patients, 13 females and four males, participated in the blindfold study. All had active rheumatoid arthritis not controlled by their current therapeutic regimens, which included corticoid analogues in five cases. The study was conducted over a period of 12 months. Each patient received medication for six months and placebo for six months, both in tablet form. Medication consisted of norethynodrel with mestranol (Enovid), a mixture of the progestogen and approximately 1.5% of the estrogen. Placebo tablets were sugar, identical in appearance with the medication. Patients were divided into two groups, selected on an alternate basis: (1) those who received medication for the first six months and placebo thereafter, and (2) those