AbstractThe aim of this paper is to compare the running behaviour of Petri nets, given by firing sequences and processes, with derivations and derivation processes in graph grammars. In a first step, Petri nets are simulated by graph grammars so that each firing in a net corresponds exactly to a direct derivation in the simulating graph grammar. In a second step the non-sequential behaviour of nets described by net processes is related to the non-sequential behaviour of graph grammars given by derivation processes. a one-to-one correppondence can be established between the processes on a Petri net and the complete conflict-free processes in the graph grammar simulating the net. This adds a new piece of evidence substantiating the close relationship between net and graph grammar theory