The pair distribution functions and the adsorption isotherms for a hard-core dimerizing fluid in disordered hard-sphere matrices have been determined using the associative extension of replica Ornstein-Zernike equations. Some grand canonical Monte Carlo simulation results for tangent hard-sphere dumbbells adsorbed in hard-sphere matrices are presented. Theoretical predictions for the structure from the solutions of integral equations with the associative hypernetted chain (HNC) and Percus-Yevick (PY) approximation agree with those from the simulations. However, the HNC closure has been found to work better than the PY one.