MarkerSize Property [Excel 2003 VBA Language Reference]

Returns or sets the data-marker size, in points. Can be a value from 2 through 72. Read/write Long.

Example

This example sets the data-marker size for all data markers on series one.

Worksheets(1).ChartObjects(1).Chart _
    .SeriesCollection(1).MarkerSize = 10

Applies to | LegendKey Object | Point Object | Series Object