Two brief patient-rated scales, the Internal State Scale (ISS) and the Self-Report Manic Inventory (SRMI), have been shown to reliably diagnose mania. In the current study we further evaluated the utility of these scales relative to each other and to the observer-rated Young Mania Rating Scale (YMRS), for quantifying the severity of manic/hypomanic symptoms cross-sectionally and over time, in 20 patients with rapid-cycling bipolar disorder. The self-report scales correlated well with each other and with the YMRS, but each covered a somewhat different domain of the manic syndrome. The SRMI and the ISS were more sensitive than the YMRS to the mood fluctuations in the euthymic to hypomanic range observed in our subjects. Used in tandem, the two self-report scales may find application in clinical research with outpatients with bipolar disorder, and as an adjunct to clinical monitoring in this patient population.