The continued increase in the number of checks printed on laser MICR printers has raised a concern about the MICR print quality produced by these devices and the resulting performance on the various high speed reader/sorters such as the IBM 3890®. This paper shows that with proper toner selection and fuser temperature settings, reader/sorter performance problems are minimized. Toner adhesion enhancement agents in the paper will improve fusing latitude but not dramatically.The adhesion failures generated by the reader/sorter are very similar to those generated using tape transfer of the toned characters. Good tape transfer measurement results will effectively predict good reader/sorter performance.In addition an attempt was made to correlate the failure modes of checks rejected by the 3890 to the readout of a conventional waveform check qualifier. The qualifier was unable to detect the same failures.