This paper considers a Monte-Carlo Nystrom method for solving integral equations of the second kind, whereby the values (z(y i )) 1≤i≤N of the solution z at a set of N random and independent points (y i ) 1≤i≤N are approximated by the solution (z N,i ) 1≤i≤N of a discrete, Ndimensional linear system obtained by replacing the integral with the empirical average over the samples (y i ) 1≤i≤N . Under the unique assumption that the integral equation admits a unique solution z(y), we prove the invertibility of the linear system for sufficiently large N with probability one, and the convergence of the solution (z N,i ) 1≤i≤N towards the point values (z(y i )) 1≤i≤N in a meansquare sense at a rate O(N − 1 2 ). For particular choices of kernels, the discrete linear system arises as the Foldy-Lax approximation for the scattered field generated by a system of N sources emitting waves at the points (y i ) 1≤i≤N . In this context, our result can equivalently be considered as a proof of the well-posedness of the Foldy-Lax approximation for systems of N point scatterers, and of its convergence as N → +∞ in a mean-square sense to the solution of a Lippmann-Schwinger equation characterizing the effective medium. The convergence of Monte-Carlo solutions at the rate O(N −1/2 ) is numerically illustrated on 1D examples and for solving a 2D Lippmann-Schwinger equation.