Sort of.
Yes, it is possible to import data from Excel, but it must be done in a very specific and precise way. In fact, what you are importing is a series of commands that create the invoice in QuickBooks.
Following is an example of a command telling QuickBooks to create an invoice:
!TRNS TRNSTYPE DATE ACCNT NAME AMOUNT DOCNUM MEMO INVITEM INVMEMO TOPRINT
!SPL TRNSTYPE DATE ACCNT NAME AMOUNT DOCNUM MEMO INVITEM INVMEMO TOPRINT
!ENDTRNS
TRNS Invoice 3/17/2003 Accounts Receivable The McIntosh Group 7.81 317.001 Printing Services Plotting/Printing Thank you! Y
SPL Invoice Kinko's D&I:SB2
allas TX North Tollway
SPL Invoice Plotting Income -9.05 Plotting/Printing Services Plotting/Printing
SPL Invoice Preferred Customer Discount 1.81 Discount Preferred Customer Discount
SPL Invoice Sales Tax Payable Oklahoma Tax Comission -0.57 OK State Sales Tax OK State Sales Tax
**********************
The above creates one invoice. QB is really weak in this area, that is conversion and importing. But, yes, it is doable, but it isn't for the weak at heart.