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Lysozyme and prophenoloxidase are two immunity-related enzymes in insect. In our attempt to understand their roles in defence, we profiled expressions of the encoding genes in Spodoptera exigua Hubner and Spodoptera litura Fabricius, during the infection process by an entomopathogenic fungus, Metarhizium anisopliae var. anisopliae. Gene expressions were analysed using quantitative real-time reverse transcription-PCR. Sampling was done at 0, 2, 12 and 24h after infection, and when the infected larvae reached the moribund stage at 36 and 60h after infection. The expression profiles of the two genes were similar in both larvae. At 24h after infection, the lysozyme gene was expressed at a higher level in the infected larvae (fivefold) when compared to the healthy larvae, and reached the highest level (13-fold in S. exigua and 7-fold in S. litura) at the moribund stage. The expression levels of the prophenoloxidase gene in the infected larvae were similar to that of the control, except for a slight increase in expression at 2 and 24h (similar to 1.5-fold) after infection. These findings provide new information on the changes in transcriptional levels of LYZ and PPO, and indicate the importance of these genes in insect defence response against fungal infection.