You can use the ListCount property to determine the number of rows in a list box or the list box portion of a combo box.
Setting
Microsoft Access sets the ListCount property to the number of rows in the list box or the list box portion of the combo box. The value of the ListCount property is read-only and can't be set by the user.
This property is available only by using a macro or Visual Basic. You can read this property only in Form view and Datasheet view.
Remarks
The ListCount property setting contains the total number of rows in the combo box list or list box, as determined by the control's RowSource and RowSourceType properties. If the control is based on a table or query (the RowSourceType property is set to Table/Query and the RowSource property is set to a particular table or query), the ListCount property setting contains the number of records in the table or query result set. If the RowSourceType property is set to Value List, the ListCount property setting contains the number of rows the value list specified in the RowSource property results in (this depends on the value list and the number of columns in the list box or combo box list, as set by the ColumnCount property).
If you set the ColumnHeads property to Yes, the row of column headings is included in the number of rows returned by the ListCount property. For combo boxes and list boxes based on a table or query, adding column headings adds an additional row. For combo boxes and list boxes based on a value list, adding column headings leaves the number of rows unchanged (the first row of values becomes the column headings).
You can use the ListCount property with the ListRows property to specify how many rows you want to display in the list box portion of a combo box.