Multimode liquid‐core quartz fibers, potentially useful for long‐distance optical communication, have been constructed. The optical transmission loss of these fibers has been measured between 6000 and 11 000 Å. Fibers filled with tetrachloroethylene or a mixture of equal parts by volume of tetrachloroethylene and carbon tetrachloride have transmission loss of 20 dB/km or less between 8400 and 8600 Å and between 10 400 and 11 000 Å. These bands are of particular interest because within them operate highly promising oscillators such as the GaAs diode and the Nd: YAG laser. An absorption peak of 80 dB/km at 9600 Å is attributed to a small percentage of OH in the tetrachloroethylene. In the wavelength intervals between 7000 and 7600 Å and between 8200 and 11 000 Å these fibers have losses lower than or about equal to those reported for any other fibers.