Adenosine is an endogenous nucleoside acting on coronary perfusion and myocardial conduction. Although the anti-arrhythmic effects of adenosine have been known for decades, interest in the use of adenosine or adenosine-triphosphate (ATP) (a precursor of adenosine) in termination of supraventricular tachycardia (SVT) has been renewed. We studied the use of striadyne (ATP and a mixture of other nucleosides including adenosine) in 22 infants younger than 6 months in order to evaluate efficiency and safety of the drug in this particular age group. Striadyne stopped SVT in 17 cases and was diagnostic in another 4 cases. Ten out of 17 successfully converted infants showed one or more reinitiations of SVT, which were easily controlled. The results support the efficiency of ATP for the termination of re-entry types of tachycardia, as well as its diagnostic value and its lack of serious side-effects.