Mycoplasma membrane protein (MMP) augmented HIV production from MOLT-4 cells chronically infected by HIV. A nearly 3-fold increase of HIV p24 antigen was detected in MMP-treated culture as compared to control culture at 100 micrograms/ml. MMP also augmented HIV production in different T cells chronically infected by HIV-1 and ARV-1. Kinetic experiment showed that HIV production was maximally elevated 24 hr after exposure to MMP. Similarly, MMP also augmented HIV-induced cell fusion and virus production in coculture. Hybridization experiment revealed that this augmentation was due to enhancement of HIV transcription.