The PhysioNet/Computing in Cardiology Challenge 2015 is now open! This year's challenge is 'Reducing False Arrhythmia Alarms in the ICU'. False alarms in the ICU can lead to a disruption of care, impacting both the patient and the clinical staff through noise disturbances, desensitization to warnings and slowing of response times, leading to decreased quality of care. False alarm rates can be as high as 90% or more. To address this issue we have developed an expert-labelled data set of 1250 life-threatening arrhythmia alarms with five minutes of electrophysiological and pulsatile waveform data leading up to each alarm event. Competitors are challenged to devise a method of processing all the available data to reduce false alarms with minimal or no effect on true (vital) alarms.