Abstract. Newborn preterm infants have large losses of fluid from their immature skin. To minimize fluid and heat loss and reduce the risk of dehydration and hypothermia, infants are routinely nursed in humidified and temperature-controlled incubators. The incubator care can be interrupted by periods of skin-to-skin care (STS). However, data are limited on how to reduce fluid and heat loss from very preterm infants during STS. To investigate the effect of clothing during STS we measured the evaporation of water from the surface of a body/skin model designed to simulate the skin temperature and ambient conditions of an extremely preterm infant during the first days of life. A semi-permeable membrane was placed on top of a water filled chamber heated to body temperature and kept in an incubator at relevant environmental conditions. The evaporation rate (ER) was determined by evaporimetry from the membrane surface alone or from the membrane covered with layers of fabric. The effect of fabric clothing was also determined in a group of extremely preterm infants during incubator care. The evaporation rate (ER) was 51 ± 2.7 g/m2 h from the membrane only. When layers of fabric were applied, ER decreased for each added layer. The ER and temperatures recorded in the model system were in the range relevant for preterm infants. In the infants, fabric clothing also resulted in a decreased ER. We conclude that layers of a simple cotton fabric provide a significant barrier to vapor diffusion thereby reducing evaporative loss of water and heat.