RASSF1 and neoplasm: Sandinha et al (2006) described a heterogenous distribution of cells displaying monosomy three in uveal melanoma and Maat et al (2007) described areas of unmethylated and methylated RASSF1a within individual uveal melanomas. It is therefore plausible that the BRAF mutation could also be distributed heterogeneously. To address this problem we studied several separate tumour areas in 11 choroidal melanomas positive for the T1799A mutation. In six of the tumours positive for the BRAF mutation it was observed that the mutation was present in some areas of the tumour but not in others.