The aim of the article is to study the Betti numbers of the tangent cone of Gorenstein monomial curves in affine 4-space. If C-S is a noncomplete intersection Gorenstein monomial curve whose tangent cone is Cohen-Macaulay, we show that the possible Betti sequences are (1,5,5,1), (1,5,6,2) and (1,6,8,3).