When someone asks the question, how good is ambulatory EEG telemetry, there is no correct answer. There are many manufacturers of ambulatory EEG technology. Each device has its own strengths and weaknesses. What one is really interested in when one asks such a question needs to be defined in terms of expectations and technical capabilities for the piece of equipment under discussion. Systems exist or can be easily modified to be as sophisticated as the best of the inpatient units. However, is that level of sophistication needed for the ambulatory based recordings? Again, the answer to that is dependent on the ordering physician's expectations. Below is a discussion of the different clinical expectations that are frequently encountered and the needed requirements for an ambulatory system to properly address them.