We describe the results of a comparison of optical-power meters undertaken by the National Institute of Standards and Technology (NIST, USA) and the Physikalisch-Technische Bundesanstalt (PTB, Germany) at nominal wavelengths of 1300 nm and 1550 nm. Both laboratories used thermal detectors as reference standards, which were compared using a germanium trap detector as a transfer standard. Measurement results showed differences of less than 1 part in 10 3 , well within the combined uncertainty for both laboratories.