Thanks Bernard but no... is not working. Lets suppose I type D as value in text box. I get this error message:
SQL: column 'D' not found.

This is my exact code in textbox LOST FOCUS event.

PUBLIC Nom
Nom=" "
STORE ALLTRIM(THIS.VALUE) TO Nom
THISFORM.combo2.ROWSOURCE=" "
THISFORM.combo2.ROWSOURCE="select nombres from alumnos where nombres LIKE " + Nom + " into cursor listnom"

Thanks in advance for your time