mySQL Data Limits

I have a database with a TEXT field in it, and I've been using it this way for over three years... today was the first time an INSERT was truncated on this field... It was an unusually large INSERT, and due to the truncation I'm now has wondering what are the limits (if any) on inserting data into a TEXT field via PHP through an HTML form? All the data was submitted (non-truncated) because an email was composed and sent out based on the form data, but the data in the database did not make it completely... thanx...