The Karhunen-Loeve transform (KLT) is applied to the analysis of dynamic sequences of thermograms describing the temporal evolution of body surface temperature following the application of an external thermal stimulus. The KLT may be evaluated either along the spatial or temporal dimensions of the data; the duality of both representations is emphasized. An example is presented to illustrate that the KLT allows an efficient data reduction and facilities tumor detection by highlighting physiologically important abnormalities in the time behavior of thermal patterns.>