The telomeric sequence cloned from Plasmodium berghei (see M. Ponzi et al. (1985) EMBO J. 4, 2991-2995) was tested for species specificity. A telomeric and a subtelomeric fragment of the cloned insert served as separate, labelled probes on pulsed field gradient electrophoretical patterns and on genomic digests from the rodent malarias Plasmodium yoelii, Plasmodium chabaudi and from the human malaria Plasmodium falciparum. Results indicate that the subtelomeric fragment, abundantly represented in two chromosomes of P. berghei, is not present in the other DNA tested, while the telomeric fragment is present in every chromosome-sized molecule in all the species tested. The telomeric location in the other genomes of the sequences homologous to the P. berghei telomeric probe is confirmed by experiments with Bal 31 exonuclease. In all cases, the TaqI site appears to delimit the common telomeric portion.