Among mammals there is usually an increased frequency of aggressive interactions when population density increases.Conducted at four zoos in southern India the study examined the effect of spatial crowding on social behaviour of three different species of ungulates,chital(Axis axis),black buck (Antilope cervicapra)and sambar (Cervus unicolor).Systematic behavioural observations were carried out both in winter and summer season between the various age-sex classes on the pattern of their behaviour across density.With incease in density, the mean aggression frequencies and severity of injuries inflicted during aggressive altercations increased. The distribution of aggression across age-sex status was not unidirectionally distributed at high- density enclosures causing intense aggression for available space and resource.The rationale for identifying the cutoff line where level of aggression intensifies and a low-density enclosure shifts to moderate and high density would aid the zoosin their captive management programmes of incorporating alternative plans for reducing species density.