A new technique of injecting insulin without a needle employs a jet injector to administer a high-pressure stream of medication. This method causes very little pain and affords great accuracy, ease of administration, and safety. The medication is more widely diffused in the body by jet injection than by the needle-and-syringe technique. The control of blood sugar (with similar doses of insulin) achieved by the two techniques is similar, and their effect on local tissues is also similar. In the patients studied, jet injection appeared to be a very satisfactory method of administering insulin and has met with good patient-acceptance. Jet injection is also a useful method for the visually handicapped.