The director of the College's biochemical laboratories left his post last week for a high-level job in the two-year-old Molecular Biology Department at Harvard affiliated Massachusetts General Hospital (MGH).

Harry W. Orf is the second Harvard biologist in the last six months to leave the College for the new department which was established two years ago under a pioneering arrangement with a West German firm.

Under the arrangement Hoechst A.G. of West Germany provides a 10 year $50 million grant to support research into recombination DNA In return, the firm receives the right to profit first from any research results, though MGH will hold all patents on discoveries.

Michael A. McGrath, department administrator of the department of biochemistry and molecular biology, is filling Orf's post until a replacement can be found. McGrath said yesterday that the Department is advertising the opening in The New York Times. The Boston Globe, and The Washington Post and hopes to fill the slot by late spring.

Orf said yesterday that he made the switch because the newly created position at MGH offered "greater opportunities for long range financial planning." By the end of 1984, the department plans to hire 100 researchers and move into MGH's Wellman Research Building, which is still under construction.

Orf's departure follows that of Frederick M. Ausubel, associate professor of Biology, who received tenure from MGH's Department of Genetics and joined its Department of Molecular Biology last fall.