In our Intensive Care Nursery, coagulase-negative staphylococcus is the most frequent blood culture isolate. As skin antisepsis is critical in preventing blood culture contamination, we examined the efficacy of the chlorhexidine tincture (CH) used in our nursery for this purpose. Staphylococcus epidermidis colonized the forearms of 88% of infants tested, in a mean density of 10(4) organisms/cm2. Following a 60-second application of CH (0.5% in 70% ethanol), bacterial growth from forearm skin remained abundant in 15/38 infants (39.4%). Cleansing with 70% isopropyl alcohol, followed by CH as above, left abundant residual growth in only 1/37 infants (2.7%) (P less than 0.001). All 136 S. epidermidis tested were susceptible to CH (MIC less than 5 micrograms/ml) and 14 of 15 exposed to CH 0.02% were rapidly killed (greater than or equal to 98% fall in viable counts within 90 sec). We conclude that two-phase antisepsis using isopropanol followed by CH is a more effective preparation for blood culture in neonates than is CH alone.