Inbred corn line, designated MN40, are disclosed. The disclosure relates to the seeds of inbred corn line MN40, to the plants and plant parts of inbred corn line MN40 and to methods for producing a corn plant, either inbred or hybrid, by crossing inbred corn line MN40 with itself or another corn line. The disclosure also relates to products produced from the seeds, plants, or parts thereof, of inbred corn line MN40 and/or of the hybrids produced using the inbred as a parent. The disclosure further relates to methods for producing a corn plant containing in its genetic material one or more transgenes and to the transgenic plants produced by that method and to methods for producing other corn lines derived from inbred corn line MN40.