Hapten-carrier protein conjugates were made using ciprofloxacin (CPFX) and two carrier proteins by 1-ethyl-3-(3- dimethylaminopropyl)-carbodiimide hydrochloride (EDC) method. Ultraviolet spectrophotometry were used to demonstrated that the molecule conjugate ratio of CPFX to ovalbumin (OVA) and bovine serum albumin (BSA) are 6:1 and 13:1 respectively. Nondenaturing gel electrophoresis results revealed that the conjugate band migrates differently from that of the carrier protein alone and of the EDC-treated protein when as few as 6 molecules of CPFX are attached to the carrier protein. The results indicate that nondenaturing gel electrophoresis and ultraviolet spectrophotometry can be employed to analyze the molecule coupling ratio of CPFX to carrier proteins qualitatively and quantitatively.