Mating and premating behaviour of the Crested Newt Triturus cristatus and the Marbled Newt T. marmoratus were studied in both the natural habitat and aquaria. Attention is focussed on male interactions. During the breeding period, males occupy open spots on the bottom of a pond defending these against other males. Such defense consists of a series of display movements, usually chasing the visiting male away. The male-male display has been interpreted as territorial behaviour. Territories are usually occupied for a period of one evening or less. Male-male encounters take place more frequently than male-female encounters. The observed behaviour has characteristics of lek-breeding.