Ultrasound-assisted ionic liquid-based dispersive liquid liquid microextraction procedure (UAIL-DLLME) was developed for determination of trace levels of patent blue V prior to its determination by UV-visible spectrophotometry. Patent blue V was extracted from 25-mL sample into a 100-mu L volume of ionic liquid, 1 -butyl- 3 -methylimidazolium hexafluorophosphate ([bmimil][PF6]), with the aid of sonication in an ultrasonic bath. Several variables affecting microextraction efficiency were optimized Under the optimum experimental conditions, the detection limit (3 s) was 0.68 mu g L-1, and the preconcentration factor was 100. The relative standard deviation for six replicate determinations of patent blue V was 4.5 A. The method was applied to the determination of patent blue V in food samples. The proposed procedure is effective, very simple, and fast.