There are 9 words that start with 'isoa'.
| isoantigen | isoantibody |
| isoantigens | isoantigenic |
| isoagglutinin | isoalloxazine |
| isoantibodies | isoagglutinins |
| isoalloxazines | |
Note: These 9 words that start with 'isoa' are found from the USA & Canada version of the tournament Scrabble word list.