In the present paper we put forward an efficient Monte Carlo (MC) cluster algorithm for the simulation of molecular self-assembly. This cluster algorithm is particularly useful for dilute system of molecules where self-assembly takes place hierarchically at different length scales. The algorithm enables an efficient simulation of molecular self-assembly which is not achievable by single molecule movements due to binding energy barriers. The self-assembly of conical particles is simulated with this algorithm to illustrate its performance and its possible optimization. (C) 2008 Elsevier B.V. All rights reserved.