Difficulties in obtaining appropriate blood pressure control are one of the main reasons for referring patients to hypertension specialists. Primary care physicians may undertake some steps to confirm the diagnosis of resistant hypertension, seek some modifications of the therapeutic regimen that would render the referral unnecessary, and even find some diagnostic clues suggesting the presence of secondary hypertension that would benefit from a further work-up in a specialist centre. Advice presented in this review should allow more rational referral of patients with uncontrolled blood pressure to hypertension specialists.