Initial notions of cooperative/synergistic interactions between D-1 and D-2 dopamine receptors have been followed by recent evidence suggesting more complex forms of D-1:D-2 interaction. Each of the new, putative selective D-1 antagonists SCH 39166, NO 756 and A-69024 antagonised typical behavioural responses to the selective D-2 agonist RU 24213 and concurrently released atypical behaviour. These data extend new notions of both cooperative/synergistic and oppositional D-1:D-2 interactions in the regulation of typical and atypical behaviours, which may involve further subtypes of D-1 and of D-2 receptor.