Both parametric and implicit representations are used in,a variety of computer vision applications such, as object modeling, recognition and pose estimation. In this paper, we present a new algebraic curve fitting technique based on the implicitization of affine invariant Fourier descriptors that can be used to model free-form objects captured from different viewpoints. Implicitization can be carried out quite efficiently using a numerical procedure rather than computing determinants of eliminant matrices, symbolically. Affine invariance of the proposed fitting technique is experimentally shown on a database of 2D free-form objects. Experimental results, are provided to assess the robustness of our fitting method under data perturbations. Some invariant recognition examples are also presented.