A list of diatoms found on the higher algae Centroceras sp., collected at Itanhaém, State of São Paulo, Brazil, and Ectocarpus sp. and Caulerpa racemosa from Ubatuba, also in the State of São Paulo, Brazil, is given in this paper. Only onq species Licmophora abbreviate Agardh is typically epiphitic. Nine different species and the genus Auricula, are here recorded for the first time for Brazil. A new species Navicula melchersi is described. The difference of the surrounding conditions, calm waters at Ubatuba and breakers at Itanhaém, probably accounts for the species composition of the communities from the two places.
