A simple and rapid method using electron capture detector gas chromatography (GC-ECD) was developed for the determination of hexachlorobenzene (HCB) in Food Red Nos. 104 and 105. The sample was dissolved in water and HCB was extracted with hexane. The GC-ECD operating conditions were as follows: column, InertCap 5 MS/NP (30 m x 0.25 mm i. d. with 0.25 microm film thickness); oven temperature, 60 degrees C(1 min)-->20 degrees C/min-->150 degrees C(10 min)-->20 degrees C/min-->280 degrees C(5 min); inlet temperature, 260 degrees C; detector temperature, 300 degrees C; carrier gas, nitrogen (constant press 25 psi); inlet mode, splitless. For the evaluation of the method, HCB spiked into R104 and R105 at the levels of 2 microg/g and 5 microg/g was determined in replicate in five laboratories. Mean recoveries of HCB from R104 and R105 were 98.2-103.7%. Repeatability relative standard deviation values were 2.9-6.0% and reproducibility relative standard deviation values were 4.2-9.3%. HORRAT value was less than one. From these results, the validity of this method was confirmed.