The orthostatic circulatory reaction, the physical working capacity on a bicycle ergometer, the blood pressure reactions at rest both during and after the ergometer test, the total hemoglobin content and the heart volume in the supine position were all determined on four separate occasions in 34 nulligravidae who were taking a low estrogen dose steroid oral contraceptive consisting of 30 micrograms of ethinyl estradiol and 150 micrograms of levonorgestrel (known as Neovletta, Schering AG). These examinations were performed once prior to the commencement of this medication, and 6, 12 and 24 months thereafter. The orthostatic pulse and blood pressure reactions taken on these subjects standing upright for a period of eight minutes were pronounced up to and including the 12 month control, but decreased thereafter. Physical working capacity at a pulse rate of 170 beats per minute on the different test occasions decreased up to and including the 12 month control, but thereafter seemed to increase almost to their initial levels. Blood pressure, heart volume and total amount of hemoglobin increased up to and including the 12 month control but thereafter seemed to return to the pre-treatment level. These circulatory changes during the first year of the application of this contraceptive may be as the result of a marked sympathicotonic reaction induced by the steroids. Possibly because of some form of adaptive mechanism, this reaction seems to decrease (and almost to "normalize") during the second year of use.