Segregation of particles during the filling of a vessel was investigated for mixtures of multi-particle sizes. The effects of the particle feed rate, initial concentration of the components in the feed mixture and the number of components (l = 2-5; particle diameters between 0.174 and 1.66 mm) were examined on the segregation pattern in a two-dimensional silo. The results revealed that the degree of segregation became pronounced at low feed rates and at low initial concentrations of the smallest component. The segregation index initially increased and then decreased with increasing number of components. A correlation for a proposed segregation index was developed in terms of the operational parameters of the system and the correlation was found to adequately describe the data.