Description: This data set contains profiles of atmospheric carbon monoxide (CO) concentrations retrieved from measurements made by the Kiruna Microwave Radiometer (KIMRA), housed at the Swedish Institute for Space Physics, Kiruna (67.8° N, 20.4° E). The data is retrieved on a standard pressure grid that is 62 layers, spaced approximately equally in altitude between 2km and 124 km. The current time range of the data is December 2008 to May 2015, with data gaps corresponding to Summer periods when the CO concentrations in the middle atmosphere drop to very low values, or to non-operation of the instrument. The average altitude range (over the entire KIMRA CO dataset) of reliable information is 48-84 km. Data is generally considered reliable where the measurement response is above 0.8, but there are important caveats discussed in Ryan et al. (2017). If the CO profiles are being compared to another data set with significantly higher altitude resolution, the averaging kernel matrix should be used to smooth the higher resolution data. The error in a profile from statistical noise on the measured spectrum is also provided, as well as estimates of the errors from other sources. This work has been funded by the German Federal Ministry of Education and Research through the research project: Role Of the Middle atmosphere in Climate (ROMIC, https://romic.iap-kborn.de).