Within the first days of life, 10 infants, of 32 weeks' gestational age or less, began 2 weeks of treatment with a semipermeable wound dressing over a small area of skin. The effects of the dressing on transepidermal water loss and cutaneous microflora were evaluated. Transepidermal water loss from the semipermeable dressing-treated skin was significantly less than that from the untreated skin immediately after placement of the dressing (8.1 +/- 1.8 g/m2.h-1 vs 17.7 +/- 3.5 g/m2.h-1, P less than .0001). The normal accelerated skin maturation process that occurs in these infants continued beneath the semipermeable dressing. The number of gram-negative bacilli or other bacteria did not increase beneath the semipermeable dressing beyond that seen on the untreated site. Malassezia furfur was found only on the control site, never beneath the semipermeable dressing. According to results of this preliminary study, a semipermeable dressing can be safely used in premature infants and the use of a semipermeable dressing may decrease the excessive transepidermal water loss associated with prematurity.