The nature of gravitational forces exerted by topological defects on surrounding matter in the frame of Brans-Dicke theory of gravity (BD) is investigated. Comparison is made with the corresponding cases in General Relativity (GR). The role of the scalar field as a weakener agent of the strength of gravitational forces due to pressure terms is discussed. PACS Nos.: 04.20Jb, 98.80.Cq Amongst the most curious properties of space-time generated by the so-called topological defects (vacuum domain walls, strings, monopoles and textures) lies the appearance of repulsive gravitational forces arising from negative pressure terms, present in the energy-momentum tensor of these structures. 1 The gravitational interaction of vacuum domain walls, strings, monopoles and textures with surrounding matter has been studied both in the frameworks of general relativity 2-5 and Brans-Dicke theory. 6-8 In most of these cases the results have been obtained for weak gravitational fields. It is well known that in the weak field approximation the metric tensor may be written in Galilean coordinates as g µν (x) = η µν + h µν (x), where η µν = diag(1, −1, −1, −1) and |h µν | 1. In the case of Brans-Dicke theory of gravity it is also assumed that the scalar field φ is to be written as1, ω is a dimensionless parameter and G is the Newtonian gravitational constant. 9 On these assumptions, the linearized field equations of general relativity and Brans-Dicke theory are given, respectively, by − h µν + h γ µ,ν,γ + h γ ν,µ,γ − h ,µ,ν = 16πG T µν − η µν 2 T ,