Many visualization tools have been designed to aid information processing during whole genome projects. We have developed a trace viewer program, ChroView, which can read a chromatogram file and display the chromatogram traces of the four bases. The program can be used to examine sequencing quality and base-calling errors. It can also help researchers to edit and save base-calling results while browsing the traces. Additionally, this program has a basecalling feature which can produce supplementary data for validation of the results from other base-calling programs.