PURPOSE: To determine if temperature probe covers contribute to nosocomial infections by providing an environment for skin microbe colonization. DESIGN: Descriptive, comparative design with infants randomized into two groups: foam probe cover and hydrogel probe cover. Skin cultures were obtained 72 hours after cover placement. Bacterial growth was quantified after 24 and 48 hours. Skin integrity was assessed using visual irritations scores (VIS) every 5 minutes for 30 minutes following cover removal. ANOVA and ANOVA-RM were used to compare amounts of microbes and VIS scores between groups. SAMPLE: Twenty-six medically stable infants, 29 to 34 weeks gestational age, less than 10 days postbirth, and in an incubator. MAIN OUTCOME VARIABLE: Microbial growth and VIS. RESULTS: There were no statistically significant differences in microbial growth and VIS scores between groups (p > .05). Clinical significance was noted in VIS scores. Infants who had foam covers had more sustained irritation scores.