The present invention is directed to a method for cloning and producing the HinPI restriction endonuclease by (1) introducing the restriction endonuclease gene from Haemophilus influenza P1 into a host whereby the restriction gene is expressed; (2) fermenting the host which contains the vector encoding and expressing the HinPI restriction endonuclease, and (3) purifying the HinPI restriction endonuclease from the fermented host which contains the vector encoding and expressing the HinPI restriction endonuclease activity.