In the acute experiment six healthy volunteers were given orally two doses of lithium chloride, 16 and 32 mmol, and placebo sodium chloride 32 mmol in a double-blind standardized procedure, with a 1-week interval between treatments. Compared to sodium, lithium produced a decrease in subjective well-being, decrease of skin conductance fluctuations, and increase in plasma calcium concentrations. Dose-related effects were maximal at the first hour after ingestion, decreasing or disappearing at 3--5 h. Most effects did not correlate with plasma or erythrocyte lithium concentrations, but drug effects and feelings of nausea were highly correlated. Accordingly, most acute effects seemed due to peripheral drug effects. In the chronic experiment six healthy volunteers were given orally 16 mmol of lithium chloride or sodium chloride (placebo) twice a day for 1 week in a double-blind standardized procedure with a 2-week interval between treatment weeks. Compared to placebo, lithium produced feelings of subjective impairment, an increase in EEG slow waves and of auditory evoked response variability, a deficit in long-term memory, and an increase in plasma magnesium concentrations. Most lithium effects did not correlate with plasma or erythrocyte lithium concentrations.