A method of delivering particles into a cellular specimen such that there is minimal disruption or damage to the specimen. In accordance with the method, a monodispersion of tiny acicular magnetizable particles is formed and that dispersion is placed in contact with the specimen. Then the dispersed particles are subjected to a nonuniform converging magnetic field having an axis of convergence which intersects a selected target area in the specimen and whose field lines converge to a focal point proximal to the specimen. Under the influence of the field, the particles align themselves with the field lines and travel into the specimen toward the focal point beyond the specimen. The method may be used to deliver particles at the cellular, microbial, tissue and organ levels and the agents that are deliverable by the method run the gamut from radiation, heat, DNA and diverse biological and chemical materials. Apparatus for practicing the method at these different levels are also disclosed.