Distinct noises are emitted when agglomerates impinge on the walls of the agglomeration vessel in the process of agglomeration in an organic liquid. In addition, the turbidity of the suspension changes from opaque to transparent during the progress of agglomeration. On-line monitoring for agglomeration in an organic liquid was investigated by measuring the agglomeration noises and the turbidity of the suspension by laser attenuation. The relative energy of the noises emitted during the process of agglomeration was shown to be a function of agglomerate diameter and recovery. Recovery was correlated with the amount of attenuation of the laser beam in the suspension. From these results, the technical feasibility of on-line monitoring of the agglomerate＇s diameter and recovery was demonstrated by measuring relative energy and laser attenuation.