Objectives: To determine the optimum time for developer exchange in radiology department using spectrophotometry. MATERIALS AND METHODS: Maximum absorption wave lengths were measured for various kinds of developer agents using spectrophotometry in last day of developer work during the last day developer use in three hospitals. Samplings were also done from the first to last days of developer usage for hospitals and the corresponding curves were provided. RESULTS: Results showed that maximum absorption wavelengths are dependent on developer type and the outset of plateau part of optical density versus day of usage curves could be considered as optimum time for exchange. CONCLUSION: Spectrophotometry is a simple and gratis method and helps us to avoid errors in experiential determining of developer exchange time. This method doesn’t need to sophisticated systems and can be simply done using a conventional spectrophotometer which can be easily found in each medical laboratory, often adjacent to a radiology department.