A Cavity-Biased (T,V,μ) Monte Carlo Method for the Computer Simulation of Fluids Abstract: Q modified sampling technique is proposed for use in Monte Carlo calculations in the grand canonical ensemble. The new method, called the cavity-biased (T,V,μ) Monte Carlo procedure, attempts insertions of new particles at randomly selected points. Calculations on supercritical Lennard-Jones fluid showed an 8-fold increase in the insertion process using the new method. The highest density that can be successfully treated was raised by 35 per cent, making part of the liquid region of the Lennard-Jones fluid now accessible to theoretical study by this method.