A flow injection spectrophotometric method for the assay of ciprofloxacin was developed. The method was based on the chelation of iron(III) with the drug in 0.023 mol dm-3 sulfuric acid solution in a 72 cm long coil and the brown-red complex produced was monitored at 447 nm. The super modified simplex computer program was employed for the optimization of the system and chemical parameters with respect to throughput and sensitivity as a measure of system performance. A working range for ciprofloxacin determination of 50-500 ppm for a 110 mm3 sample size with an optimum of 250 samples per hour was achieved with a relative standard deviation of less than 0.92%. The method was successfully applied to the determination of ciprofloxacin in drug formulations.