Numbers of lianas ≥2 cm gbh were recorded on trees ≥30 cm gbh in two 4 ha plots of dipterocarp forest. Associations between lianas and trees of the 12 commonest families and 16 commonest species were analysed. Liana density was 882 ha-1. Fifty-seven per cent of trees supported lianas and the mean number lianas per tree was 2.1. Lianas were highly aggregated on individual trees in most families; numbers of lianas per tree followed the negative binomial distribution for the Dipterocarpaceae but not Euphorbiaceae. Dipterocarpaceae and Euphorbiaceae differed in susceptibility, with 41 and 64% of their trees respectively supporting lianas. The proportions of trees with lianas (i.e. % trees laden) were correlated between plots at the species, but not the family, level. They were not related to tree girth; differences in proportions between families and species were maintained for trees in the 30–40 cm gbh class. At the species level, proportions of trees with lianas and the mean number of lianas per tree were significantly inversely correlated with mean branch-free bole height of trees in the 30–40 cm gbh class. Increased branch-free bole height and associated branch shedding may therefore decrease the susceptibility of trees to lianas and explain the lower susceptibility in the Dipterocarpaceae than the Euphorbiaceae.