Moses Malone -- Cause of Death ... Heart Disease

NBA great Moses Malone died due to a severe hardening of his arteries ... TMZ Sports has learned.

The Medical Examiner's Office in Norfolk, VA tells us Malone suffered from hypertension and atherosclerotic cardiovascular disease. The condition likely induced a fatal heart attack or stroke.

60-year-old Malone, one of basketball's greatest centers of all time, died Sunday morning in a Norfolk hotel. Paramedics arrived, and tried to revive him, but were unsuccessful.

Malone, known as the "Chairman of the Boards" ... played 19 years in the NBA, and was a Hall of Fame inductee in 2001.