Primary hyperaldosteronism (PHA) is regarded as a rare disease with prevalence rates of 0.5 to 2% within the hypertensive population. Recent studies using more detailed screening procedures in small hypertensive cohorts have suggested that PHA may be more common than previously thought (3-18%). Since a validated and cost-effective routine screening protocol for this entity is not established, many clinicians are reluctant to consider PHA as an underlying cause for a patient's high blood pressure. The insufficient perception of PHA may have fatal consequences since most patients are curable by an operation and missing the diagnosis often leads to significant and irreversible end-organ damage. This review focuses on the diagnosis of PHA and gives a rational and cost-effective flow chart for routine screening and differential diagnosis of PHA in hypertensive patients.