Denaturing gradient gel electrophoresis was used to identify bacterial communities from Gedongsongo hot spring, Indonesia, by culture-independent and -dependent procedures. Predominant species were found to be closely related to beta-proteabacteria, particularly from genus Ralstonia and Delftia. Other species present include alpha- and gamma-proteobacteria and Thermus groups. Some of the strains showed unique 16S rDNA sequences.