Detailed analysis of stored electrograms is essential for the interpretation of arrhythmias, programming changes, and optimization of the medical therapy in patients with implanted pacemakers and defibrillators. The physician who cares for patients with implantable electrical devices has to be able to understand the detection and treatment algorithms of those devices. Biotronik pacemakers of newer generations are capable of storing intracardiac electrograms. Earlier devices store up to 12 electrograms of 10 s duration after certain trigger events, like atrial tachycardia or high ventricular rates. Cardiac resynchronization systems can store electrograms after patient activation with magnets in addition to the above mentioned trigger-activated electrograms. Defibrillators store intracardiac electrograms during tachycardia episodes with near-field and far-field electrograms of the right ventricular lead in addition to the markers in single and dual chamber defibrillators (in addition to an atrial electrogram) and near field electrograms of the atrial, the right, and the left ventricular electrode in addition to the markers in resynchronization systems. Each channel has a maximum storing capacity of 32 min. If there are more episodes than storing capacity, electrograms of older episodes will be overwritten, but if the newer episodes are all classified as supraventricular, the last two ventricular episodes (VT or VF) will remain in the episode memory. This article describes stored electrograms, detection, and treatment algorithms of implantable cardiac devices manufactured by Biotronik.