Six glacial cover maps of Cordillera Blanca in Peru were prepared using the band ratio (TM4/TM5) of Landsat 5 TM, ETM+4/ ETM+5 of Landsat 7 ETM+ and OLI5/OLI 61 of Landsat 8 images. This cover varied between 618±60 km2 in 1987 and 449±56 km2 in 2016. In spite of differences in mapping methodologies, our glacial cover estimates are comparable with those of other studies, given an uncertainty margin of around ± 10 %. Since 1930, when the glaciers covered ca. 830 km2, the Cordillera Blanca has lost 46 % of its cover in 86 years. A nonlinear-, second-degree polynomial has been fitted to the glacier cover evolution overtime, showing that the negative rate of change has increased between the 80's (5 km2 y-1) and 2016 (23 km2 y-1). Considering altitude, the decrease in cover is particularly notable between 4500-5000 m and 5000-5500 m, and changes in the latter altitude are becoming more dominant over time (over 60 %). To explain the minor fluctuations in glacier cover around the global trend, the yearly rate of cover change was regressed against the mean Oceanic Niño Index for six periods between 1987 and 2016. The inverse relationship shows a certain amount of dispersion, that has yet to be explained, but is nonetheless significant. Keywords : remote sensing; Landsat; Snow index; band ratio; Andes; climate change; glaciology; El Niño/La Niña.