A growing body of experimental evidence indicates that rubidium possesses unique neurophysiological characteristics in animal systems, suggesting a need for investigating its antidepressant potential in humans. Lithium, an element in the same periodic series, has been used successfully in the treatment of mania. A number of studies have demonstrated that rubidium and lithium have contrasting behavioral, EEG, and biochemical properties. Over a period of 20 to 86 days. five depressed patients received varying doses of rubidium chloride, up to a maximum of 370 mEq. retained. No immediate or long-term side effects were recorded in this preliminary dose range. Behavioral and metabolic data are presented for these patients, along with a discussion of the safety factors.Abstract Teaser