Abstract : We propose an algorithm to segment 2D ellipses or 3D ellipsoids. This problem is of fundamental importance in various applications of cell biology. The algorithm consists of minimizing a contrast invariant energy defined on sets of non overlapping ellipsoids. This highly non convex problem is solved by combining a stochastic approach based on marked point processes and a graph-cut algorithm that selects the best admissible configuration. In order to accelerate the computing times, we delineate fast algorithms to assess whether two ellispoids intersect or not and various heuristics to improve the convergence rate.