A new method for amplification and labeling of RNA is assessed that permits gene expression microarray analysis of formalin-fixed paraffin-embedded tissue (FFPET) samples. Valid biological data were obtained using gene expression microarrays of diffuse large B-cell lymphoma (DLBCL) FFPET samples. We examined 59 matched DLBCL patient samples, FFPET, and fresh/frozen. The samples contained both prognostic subgroups of DLBCL: germinal center B-cell (GCB) and activated B-cell (ABC). Fresh/frozen (FF) samples were amplified by both the traditional Eberwine oligo-dT method and a new method described herein. The matching FFPET samples were also amplified using the new method. Here we detail the comparison of results from all three datasets of matched samples. An established classification model built from previous data accurately classified these new samples. This new method provides a useful technology advance for microarray analysis of FFPET archival samples.