Clinical evaluation of the thyroid status of a woman can be erroneous. Thyroid function tests can delineate the relatively hypothyroid woman—a patient whose symptoms, appearance and psychomotor activity resemble those of the true hypothyroid but whose thyroid tests are in the low-normal hypothyroid borderline range. Subjective and objective responses to thyroid medication are dramatic. In this study of 243 women, the state of relative hypothyroidism is described. Recognizing and treating this condition are responsibilities of the obstetrician and gynecologist.