Customized silicon diode detectors are widely used for elementary particle detection for their good spatial resolution. Silicon detectors are also excellent X-ray detectors in the energy range of interest for applications in synchrotron radiation experiments and, with small elements laid out in a two-dimensional array, may provide high performance imaging devices for future diffraction experiments. These pixel detectors are still in the development phase but some are already installed in experiments and within the next few years large area detectors with fast, two-dimensional readout are likely to be available for online acquisition of diffraction patterns. This article describes the technology of silicon pixel detectors and outlines the status of current developments and the performance which could be achieved in a realistic system, indicating the steps required to implement it.