Until quite recently, electron microprobe analysis techniques were limited to samples of “infinite” thickness, that is, to samples thick enough such that the entire excitation volume was contained within the material of interest. Thin film analysis was not possible with available matrix correction programs, which were based on the assumption of samples of “infinite” thickness. Now however, algorithms are available that permit analysis of thin samples.We have obtained one of the more versatile and sophisticated of these programs. In order to investigate the accuracy of this routine we have analyzed several BiSrCaCuO thin films at 15 kV and repeated the analysis at 30 kV. These films were thick enough such that at 15 kV conventional ZAF data reduction yielded acceptable totals (98-101 %) with minimal substrate x rays observed. At 30 kV, however abundant substrate x rays were observed and ZAF yielded very low totals. X-ray intensity ratios from 30 kV runs were used to estimate film thickness and matrix corrections were applied using the Waldo algorithm.