Abstract: A portable electrocardiogram storing apparatus has an electrocardiogram amplifier, an A/D converter for sampling the amplifier output and converting it into a digital signal, a patient actuatable switch, a plurality of electrocardiogram memories, and means for selecting one of the memories for storing the digital signal when the switch is actuated. A time memory is also provided for storing a time when the apparatus is set, and a timer measures a lapse time after the setting. A selected electrocardiogram memory also stores the content of the timer at the time a respective digital signal is stored therein.