Résumé : A study has been made of the production of hyperfragments by the interactions of 800-MeV/c K- mesons in nuclear emulsion. The frequency of production, estimated to be 5.3±0.3%, is about the same as for K- mesons at rest. The hyperfragments are emitted predominantly in the forward direction and the ratio of nonmesonic to mesonic decays has been found to be 11.5±0.6, much greater than for K- mesons at rest. The proportion of hyperfragments of short range (range in emulsion <5 μ) is also much greater. These and other observations indicate that the hyperfragments are heavier than those produced by K- mesons at rest. In at least 65±4% of cases they come from heavy emulsion nuclei, in contrast to the situation for K mesons at rest where most hyperfragments appear to originate in light emulsion nuclei. A model is proposed which can account for many of the features of the hyperfragment production process. © 1962 The American Physical Society.