The Monte Carlo technique is used to calculate the order parameter, Phi , of the four-dimensional spin-¹/₂ Ising ferromagnet in a simple hypercubic lattice. The order-parameter data are described by Phi (t)=B(-t)^1/2 mod ln(-t) mod ^1/3(1+Q ln mod ln(-t) mod / mod ln(-t) mod ) in the range 0.01<or approximately=-t identical to (T _c-T)/T_c<0.56 with parameters B=1.543+or-0.002 and Q=-0.030+or-0.02. The form of Phi (t) agrees with that predicted by renormalisation group theory.