Red blood cell NMR relaxation times T1 and T2 and water content were measured in ill and recovered patients with mania, unipolar depressed phase, bipolar depressed phase and control subjects. The results suggest that relaxation times are elevated in ill bipolar manic and ill unipolar depressed patients but are normal in both groups in the recovered phase and in ill bipolar depressed patients. Relaxation times therefore seem to be state-dependent but behave differently in unipolar and bipolar patients.