Without an understanding of the physiology of the Eisenmenger state (complex, syndrome or reaction) the management and outcomes of such cases will not be optimal. This is a problem for many patients scattered as occasional curiosities in practices and non-specialised clinics. The patient group with Eisenmenger reaction can lead adequate though symptomatic lives until late middle age or longer, but survival beyond age 50 years demands optimum care and attention from informed cardiologists. The cardiologist in charge should advise on lifestyle and all therapy, particularly for other systems, prevent disaster and educate patient and profession to keep the patient alive.