You can have any major and move onto PA school as long as you take the required courses for your desired graduate program (although most students usually major in science).  Each Physician Assistant (PA) program you apply to can have slightly different requirements, so be sure to investigate those schools you are most interested in to satisfy their prerequisites. In general, most places require these undergraduate courses:

• Biology: five laboratory/lecture courses from a Biology Department to include at least anatomy and physiology and microbiology. (Biochemistry is recommended.)
• Chemistry: four laboratory/lecture courses from a Chemistry Department, to include at least organic chemistry.
• Psychology: one course in psychology (Developmental or abnormal psychology is recommended.)
• Statistics: at least one statistics course and possibly another math course, like calculus.
• Humanities: at least five courses in the humanities are required
• English composition and literature
• Medical terminology
• Other recommended electives include: genetics, medical ethics, nutrition, abnormal and developmental psychology.

NOTE: Please check your school of interest for their unique requirements.  For example, some require a semester of Physics.  Physician Assistant programs usually require a minimum of 200 (some programs require 500) hours of PATIENT CARE EXPERIENCE or a combination of health care experience and research.