Candida infection of devices is common and invariably associated with biofilm growth. Exploratory microarray studies were undertaken to identify target genes associated with biofilm formation from an in vivo catheter model over time. We compared messenger RNA levels from Candida albicans grown in an in vivo central venous catheter biofilm model at 12 h (intermediate growth) and 24 h (mature) to in vitro planktonic cells without a biofilm substrate, using C. albicans oligo arrays. A total of 124 transcripts were similarly up-regulated at the 12- and 24-h time points. Ontology categories most highly represented included energy/metabolism (12%), carbohydrate (10%), and protein (13%) synthesis and modification, and transport (6%). Numerous genes were previously identified from in vitro biofilm studies. These genes included those associated with hyphal growth, amino acid metabolism, adherence, drug resistance, ergosterol biosynthesis, and beta-glucan synthesis. In the current data set, adherence genes were unique to those from the earlier time point. Differences between the current in vivo biofilm expression data and that previously reported from in vitro models, including alterations in metabolism and carbohydrate processing, may be due to the continuous availability of nutrients from host serum and the incorporation of the host-pathogen interaction.