To study the inductive expression of human phosphodiesterase 4A (hPDE4A) in yeast cell GL62 and investigate the inhibitory effects of theophylline, rolipram, and acetamide-45 on PDE4A activity of the expressed product in yeast cell GL62. METHODS: Yeast cell GL62 were transfected with human PDE4A gene cloned in the expression plasmid p138NB. Expression was induced by adding CuSO4 to a final concentration of 150μmol/L, and the expressed product was extracted. The activity of PDE4A was detected by HPLC. RESULTS: Yeast cell GL62 expressed a certain protein at CuSO4 150μmol/L, the size of the expressed product was between 62 kDa and 83 kDa, the activity of PDE4A of the expressed product at 3 h was in maximum (188±23)μmol×g-1×min-1, and the Km was (17.7±2.6) mmol/L. Theophylline, rolipram, and acetamide-45 could inhibit the activity of PDE4A extracted from yeast cell GL62. The IC50 (95% confidence limits) of theophylline, rolipram, and acetamide-45 were 1642 (989-2727), 4.58 (3.45-6.08), and 275 (170-444) mmol/L respectively. CONCLUSION: PDE4A expressed in yeast cell GL62 is biologically active. Theophylline, rolipram, and acetamide-45 can inhibit the PDE4A activity. The expressed product in yeast cell GL62 may be used in the research work of PDE4 and its inhibitors.