S.D. Codified Laws § 58-38-1
Five or more natural persons of full age and of either sex, all of whom are residents of this state and citizens of the United States, may form, under the provisions of the laws of this state relating to corporations, so far as those provisions are applicable and are not inconsistent with the provisions of this chapter, a nonprofit medical and surgical service plan corporation for the purpose of establishing, maintaining, and operating a nonprofit medical and surgical plan, whereby medical and surgical service may be provided at the expense of said corporation by duly licensed physicians and surgeons, to such of the public as become subscribers to said corporation under a contract which entitles each subscriber to medical and professional care. Such corporation shall be governed by this chapter and shall be subject to regulation and supervision by the director as hereinafter provided.
SDCL 58-38-1