Human alpha (1)-antitrypsin was produced by genetically engineered rice cells using promoter and signal peptide of a rice alpha -amylase isozyme. Batch and continuous cultures were employed to investigate the effects of alternative carbon sources on the al-antitrypsin production. While this expression system is inducible by sugar depletion, we have found that the productivity of alpha (1)-antitrypsin increased 2.4- to 3.4-fold, compared with the control medium without carbon source, in medium containing an alternative carbon source, such as pyruvic acid and glyoxylic acid. The accumulated alpha (1)-antitrypsin in the medium containing pyruvic acid reached 18.2-24.2 mg/g-dry cell in 50-70 h by batch culture.