The ^12^C/^13^C isotope ratio is a tracer of stellar yields and the efficiency of mixing in the ISM. ^12^CH^+^/^13^CH^+^ is not affected by interstellar chemistry, and is the most secure way of measuring ^12^C/^13^C in the diffuse ISM. R=^12^C/^13^C is 90 in the solar system. Previous measurements of ^12^CH 3957.7,4232.3 and ^13^CH 3958.2,4232.0 absorption toward nearby stars indicate some variations in ^12^C/^13^C, with values ranging from 40 to 90 suggesting inefficient mixing. Except for the cloud toward Oph, these R values are strongly affected by noise. With UVES on the VLT we have improved on the previous interstellar ^12^C/^13^C measurements. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************