We used principal component analysis to develop measures (called Z-parameters in this study) which reflect the diversity of codon usage in Escherichia coli genes. Protein production levels for 1500 CDSs (protein-coding sequences) identified by E.coli genome projects in Japan and the US were estimated from a correlation equation between Z1 and cellular protein content obtained through analysis of the genes experimentally characterized. Through the profile analysis of Z1 for E.coli sequences obtained by the Japanese Project, we predicted an additional 36 CDSs that had not been annotated in the International DNA Database. Thirty-one out of the 36 CDSs could be assigned to presumptive protein genes through a BLASTX search for recent protein databases in the Genome Net in Japan. Detailed examination of the Z1-parameter profile led us to assess sequencing errors which cause frame-shift.