The present study evaluated 20 patients (18 females and 2 males: mean age 55 +/- 8.8 years) suffering from major depression who had been treated with 360/720 mg/die rubidium chloride for 60 days. A gradual and significant improvement in depressive symptoms (HDRS and Zung Scale) and anxiety (Stai X1 and HamARS) was reported. Serum levels were not correlated to clinical improvement. Slight adverse effects were also observed (diarrhea and skin rashes). Rubidium chloride showed a marked and rapid anti-depressive action which was particularly evident in relation to mood, anti-conservative ideas, work, occupational interests and psychomotory slowing-down. It is clear that these symptoms represent the most important aspects of the polymorphous depressive syndrome and, in some ways, this improvement should be interpreted as the effective influence of the drug on the biological contest of mood changes.