Antibiotic-resistant Streptococcus pneumoniae (26 strains) and Streptococcus bovis (28 strains), devoid of R plasmids, were examined for DNA-DNA homology to Tn916 and Tn3701. Tn916-like structures were found in 17 S. pneumoniae and 21 S. bovis strains. Tn916-modified structures were present in 6 S. pneumoniae and 2 S. bovis strains. Two strains of each species carried elements having a Tn3701-like composite structure. All these elements were chromosome-borne. No chromosomal elements were detected in 1 S. pneumoniae and 3 S. bovis strains.