Design patterns describe solutions that can be used in a particular context for commonly recurring problems at the detailed design level of a software system. Patterns have become an important concept in object-oriented development and their usage is a widely accepted practice. This thesis investigates issue of tool support for design patterns usage that can be offered by UML modelling tools, and proposes UML based method and notation for specification of the patterns, and documentation of their instances in a design model, facilitating such support. Different ways of such support are presented and classified, and comparison of tools offering assistance for patterns usage is depicted. UML profile supporting specification of structural aspects of solutions proposed by design patterns, and documentation of their instances is specified in the thesis.