By combining techniques in High Energy Physics (Multiwire Proportional Counter) with the state of the art in Digital Electronics (Mass Core Memory) we were able to set up a prototype of a computer controlled "Multireflection Diffractometer" for protein crystallography. The prototype system has been used to collect data about thirty times faster than with the standard diffractometer (about 1400 reflection intensities per hour versus 50 reflection intensities per hour). The precision of the new data is also better with an intensity reliability R factor of 5% as compared with 6.7% from the diffractometer data. At this time about a million intensity measurements have been collected with this system on five different protein molecules. Continued financial support is solicited for a two-fold effort: a) to continue the technical development both in multiwie counter technique and in the data collection hardware and software culminating in a new system (Mark II) that can collect data efficiently of crystals of very large unit cells (up to 400 Angstroma); b) to use both the prototype and the new system to collect data to solve the high resolution structure of target enzymes of good cancer drugs. Our aim will be to understand the mchanism of action of these enzymes and to contribute to the rational development of new drugs of chemotherapeutic importance.