Excellent function!!

But as others have pointed out holidays will invariably need to be taken into account; we have a holiday table which (simplified version) is called HCD and has one field HolidayDate (DateTime). You simply need to add a simple select calc to the end of your functions thusly:

--Start with total number of days including weekends

                (DATEDIFF(dd,@StartDate,@EndDate)+1)

              --Subtact 2 days for each full weekend

               -(DATEDIFF(wk,@StartDate,@EndDate)*2)

              --If StartDate is a Sunday, Subtract 1

               -(CASE WHEN DATENAME(dw,@StartDate) = 'Sunday'

                      THEN 1

                      ELSE 0

                  END)

              --If EndDate is a Saturday, Subtract 1

               -(CASE WHEN DATENAME(dw,@EndDate) = 'Saturday'

                      THEN 1

                      ELSE 0

                  END)

       --New calc to account for Holidays added here        

    - (SELECT COUNT(*) FROM HCD

      WHERE    HolidayDate BETWEEN @StartDate AND @EndDate)

   &nbsp

This should not detract from the original elegance of the solution as this is a simple select, not requiring cursors/loops