To the Editor: Our initial study examined whether bipolar patients who became depressed while taking a mood stabilizer were more likely to improve after the addition of a second mood stabilizer or an antidepressant. In his comment to the editor, Dr. Goldberg questioned whether our data set could be used to assess whether the patients who became depressed after a period of sustained euthymia differed in treatment responsivity from patients who became depressed after a manic episode. As Dr. Goldberg noted, our group size precluded a definitive examination of this issue; however, we were able to determine the preceding mood state for 23 out of 27 subjects in our group. We could not confidently ascertain whether four subjects who had been referred only for participation in the study had been euthymic for the 2 months preceding the onset of depression; therefore, we did not include these subjects in the analyses. We defined the euthymia-depression group as patients who had had no evidence of manic or hypomanic symptoms within the 2 months preceding the onset of the depressive episode. In contrast, the mania-depression patients had been either manic or hypomanic within the 2 months preceding the onset of depression. Of the 14 patients treated with two mood stabilizers, 10 were assigned to the euthymia-depression group, while four were assigned to the mania-depression group. Of nine patients treated with a mood stabilizer plus an antidepressant, four were in the euthymia-depression group, and five were in the mania-depression group.