The modified Yvon-Born-Green equation of Rice and Lekner is solved for a monatomic fluid with 6–12 potential at kT/ε= 2.74. The equation of state and excess internal energy are calculated and compared with Monte Carlo calculations; the agreement is good. Calculations with hard-sphere modifications and with the Kihara potential are also discussed. The Kirkwood limit of stability for the fluid phase is calculated.