Abstract: In Tris-HCl buffer solution of pH 9.66, an ionic association complex was formed by the reaction of chloramphenicol with acid chrome blue K, having its positive absorption maxmum at the wavelength of 498 nm and negative absorption maximum at 594 nm. Ranges of linearity and values of apparent molar absorptivity found at both absorption maxima were within 3.2 mg·L-1 and 3.9 mg·L-1, with their values of apparent molar absorptivity of 5.93×104L· mol-1·cm-1 and 2.32×105L· mol-1·cm-1 respectively. Based on these facts, a method of spectrophotometric determination of chloramphenicol was proposed, and applied to the determination of chloramphenicol in chloramphenicol injections and eye drops, giving values of recovery and RSD′s (n=6) in the ranges of 98.9%-101.2% and 0.8%-1.2% respectively.