In order to study regulation of rbcL gene expression, rbcL gene of chloroplast DNA (Cp DNA) from maize was cloned. Cp DNA was isolated from intact chloroplast and digested with BamHI. BamHI 9 fragment of Cp DNA containing rbcL gene was ligated to pUC19 and transformed into E. coli DH5a. This recombinant plasmid was named pRLYSl. pRLYSl was hybridized with a part of rbcL gene from rice and digested with restriction enzyme BamHI, HindIIl, and PstI. From these results, it was confirmed that pRLYS1 contains intact rbcL gene and orientation of BamHI 9 fragment of Cp DNA in pRLYS1 was determined.rmined.