Methods, apparatus, systems and articles of manufacture are disclosed to pair devices to an in-body network. An example apparatus disclosed herein includes a device capability manager to identify remote sensors associated with a candidate medical device, an encryption engine to provide the candidate medical device with hashing instructions to be applied to input values from selected ones of the remote sensors, a measurement engine to acquire input values from local sensors corresponding to the selected ones of the available remote sensors during a measurement schedule, the encryption engine to apply the hashing instructions to the input values from the local sensors, and a pairing engine to authorize the candidate medical device when an encryption key associated with the remote sensors includes a threshold indication of parity with an encryption key associated with the local sensors.