The current status, i.e., the storage density and READ—WRITE rate of magnetooptic technology is reviewed. From the discussion of subsystems, it is clear that at present magnetooptical technology is mainly aimed at high-activity data base applications. The major problems for magnetooptic technology in mass storage are storage medium and transducer cost. Results on the recent developments of solid-state injection lasers are presented. This represents a breakthrough in transducer and beam control cost that is needed for the technology. The material requirements will also be discussed. Assuming future development in the above mentioned areas, we make a technology forecast on both short term and long term basis. For the short term it seems that the improvement made in both the transducer and the storage material will ameliorate the cost performance of the technology to the point that a class of magnetooptic files consistent with the mass storage requirements can be developed. For the long term, optimistic projections in light deflection and holographic techniques enable one to configure mass storage systems with throughput that can balance that of the memory. © 1971, IEEE. All rights reserved.