A model system of 85% exfoliated normal human cervicovaginal squamous cells, 15% exfoliated rodent t-mor cells and acellular, viscous, mucus-like material was used to investigate the distribution of cells on smear preparations. Smears were made by the same individual with wooden spatulas, using traditional smearing motions. The presence or absence of normal squamous cervicovaginal cells and of tumor cells in ten randomly distributed areas was recorded. Smears made with counterclockwise circular motions contained the largest number of tumor cells, and those with zigzag strokes contained the least. Independent of the motion employed, the largest number of tumor cells was found in ring 9 and the lowest in rings 4 and 10. Some of the factors influencing the accumulation of tumor cells in certain areas of the slide may be: unequal pressure of the spatula during smearing, variations in the angle between the instrument and the surface of the slide and the displacement of tumor cells to certain areas of the preparation by overlapping smearing.