G protein-coupled receptors (GPCRs) represent the major target for drug development. Although these receptors can activate their cognate G-proteins in a monomeric form, it is now recognized that they can assemble into dimers, or larger oligomers. However, the functional consequences of such receptor assembly remain elusive. Recent data revealed an 'asymmetric' organization of some dimers when activating heterotrimeric G-proteins, while a symmetric organization may be required for the activation of other signalling pathways. Here we describe a mathematical model taking these latest ideas into consideration, and report on the expected consequences of the activation of different signalling pathways. This model helps clarify data already published, and will certainly be helpful to further explain the functional significance of GPCR oligomerization. It may help develop more specific drugs targeting a specific signalling cascade. © 2009 Elsevier Ltd. All rights reserved.