Experiments were conducted on particle deposition in granular media (deep bed filters) under the condition of unfavorable surface interactions, The data collected together with those of previous investigators constitute a sufficiently large data base on which correlations were developed to predict the extent of the reduction in particle deposition as a function of relevant operating and system variables. The new correlation equation was found to describe the experimental results reasonably well from the present experimental work or the present plus early experimental works, and appears to be much better than any other earlier correlations, The limitations of the new correlation equation, as well as those of all earlier ones, were also discussed.