It is essential to have qualitative information of a satellite instrument, images observed by the instrument, etc. The purpose of this presentation is to verify the degree of infrared (IR) detectors deterioration of the Visible Infrared Spin Scan Radiometer (VISSR) on the fifth Geostationary Meteorological Satellite (GMS-5). The International Satellite Cloud Climatology Project (ISCCP) calibration results and GMS-5 VISSR/IR raw counts of infrared channels were statistically studied. The degradation and uncertainty (noise level) were estimated from 1995 to 2001. As the result, the three GMS-5 infrared channels show no significant trend over the study period except the unstable conditions of the first year. In the end, a comparison between SST observations and brightness levels at cloud-free points is suggested as a possible verification technique.