We present the results of extensive three-dimensional off-lattice Monte Carlo simulations of two interacting spherical brushes. We have measured the interacting force in systems where curvature effects are important. Our results support a description of the force profile divided into two regimes. At short separating distances between the brushes the force is well described by the theory of Witten and Pincus, whereas at larger distances the interaction is reproduced by extending the theory of Flory for dilute polymer solutions. The overall behavior is also compared with the predictions of the phenomenological theory of Doroszkowski and Lambourne. The characteristic radial size of an unperturbed brush follows the same scaling relationship found in the star polymer systems approximation.