We have used bovine serum albumin in the preparation of peripheral blood smears and compared the morphology of leukocytes with smears prepared routinely without albumin. The albumin slides were prepared from a mixture of one drop of 22% albumin and 5 drops of EDTA-collected peripheral. Parallel evaluation of smears with and without albumin was performed on 72 cases of lymphoproliferative disorders, including chronic lymphocytic leukemia (nϭ38), chronic lymphocytic leukemia/prolymphocytic leukemia (nϭ9), splenic marginal zone lymphoma (nϭ7), chronic lymphocytic leukemia with Ritcher's transformation (nϭ6), mantle cell lymphoma (nϭ5), T cell prolymphocytic leukemia (nϭ3), large cell lymphoma (nϭ3), follicular lymphoma (nϭ1). Lymphoid cells were counted on each preparation and divided into four types of cells: small (10-15 micron), medium (15-20 micron), large (Ͼ20 micron), and smudged cells. The percentages of the four subtypes of cells on each preparation were compared. As shown in table 1, there were significant differences between the two preparations in each subtype of cells. As expected, the most conspicuous difference was in the number of smudged cells (table 1). Significant reduction in smudged cells was noted on the albumin preparation. Most importantly, the data suggests that there was a proportional decrease in smudged cells whether cells are considered small, medium, or large. Therefore the albumin preparation does not influence the relative ratio of cells in the four categories.In addition to marked decrease in smudge cells, we observed that in majority of patients with splenic marginal zone lymphoma, some of the lymphoid cells on the albumin preparation show marked irregularity in the nuclear contour and become floret shaped (See figure 1). This exaggeration of the folding and irregularity of nuclear contour was not conspicuous in other forms of chronic lymphoproliferative diseases. While the number of splenic marginal zone lymphoma examined here is small, this observation can be helpful and when observed additional diagnostic tests should be used to confirm or rule out the diagnosis of splenic marginal zone lymphoma.