The validity of the concept of fractal structure for the analysis of the projection of small flocs was examined using the data obtained from a table-tennis-ball simulation and a coagulation experiment with polystyrene latex particles. Two methods defining a fractal dimension, the box-counting technique and the enumeration of primary particles in an enclosing circle as a function of the radius, were tested for the result of numerical simulations. Comparison of the two results revealed their qualitative tendencies and the limits of their applicability. The projection of flocs was also examined using the relation between the maximum distance in the projected hoc, D-m, and the number of primary particles composing the hoc, i. The decrease of fractal dimension, D, in the lower limit of i was demonstrated both numerically and experimentally.