Mo. Rev. Stat. § 507.190
507.190 Suits against infants not to proceed without guardian ad litem.
507.190. Suits against infants not to proceed without guardian ad litem. — After the commencement of a suit against an infant defendant, and the service of process upon him, the suit shall not be prosecuted any further until a guardian ad litem for such infant be appointed.
(RSMo 1939 § 867, A.L. 1983 S.B. 44 & 45) Prior revisions: 1929 § 716; 1919 § 1173; 1909 § 1747