We assessed the impact of the use of nasal swabs or nasopharyngeal aspirates and the time from specimen collection to storage at -70 degrees C on bacterial isolation. Haemophilus influenzae was isolated significantly less often from swabs than from nasopharyngeal aspirates. Samples in transit for >3 days were half as likely to grow Streptococcus pneumoniae and H. influenzae as those in transit for < or =3 days. There was no statistically significant difference for either Moraxella catarrhalis or Staphylococcus aureus.