Aspergillus fumigatus is an opportunistic, ubiquitous, saprophytic mould that can cause severe allergic responses in atopic individuals as well as life-threatening infections in immunocompromised patients. A critical step in the establishment of infection is the invasion of airway epithelial cells by the inhaled fungi. Understanding how A. fumigatus senses and responds to airway cells is important to understand the pathogenesis of invasive pulmonary aspergillosis. Here, we analysed the transcriptomes of two commonly used clinical isolates, Af293 and CEA10, during infection of the A549 type II pneumocyte cell line in vitro. We focused our RNA-seq analysis on the core set of genes that are present in the genomes of the two strains. Our results suggest that: (a) A. fumigatus does not mount a conserved transcriptional response to airway epithelial cells in our in vitro model and (b) strain background and time spent in the tissue culture media have a greater impact on the transcriptome than the presence of host cells. Our analyses reveal both common and strain-specific transcriptional programmes that allow for the generation of hypotheses about gene function as it pertains to pathogenesis and the significant phenotypic heterogeneity that is observed among A. fumigatus isolates.