The psychopathologies underlying affective disorders are thought to involve persistent changes in the expression and function of both mineralocorticoid receptors and glucocorticoid receptors in the hippocampus. In addition, exposure to stressful stimuli can precipitate episodes in vulnerable individuals. The aim of this study is to determine if spironolactone as an adjunctive therapy is effective in improving residual symptoms in bipolar disorder. Four cases of euthymic bipolar disorder (BD) patients were treated with spironolactone as an adjunctive therapy in a private treatment sector. All patients met the DSM-IV diagnosis criteria for bipolar disorder. Clinical response was assessed retrospectively using the Clinical Global Impression Scale for Improvement. Spironolactone was effective in all patients. The four cases illustrate a clinical response to residual symptoms and improvement in stress response after use of spironolactone as an adjunctive therapy in BD. This pilot case series suggests reducing in residual symptoms, with spironolactone as an adjunctive therapy in these DSM-IV BD patients. Mineralocorticoid receptors antagonists' role in reducing stress-induced symptoms deserves further investigation through placebo-controlled trials.