Not sure if the following rule (or Immigration Act) still applies, copied from Chapter 2 of Order of the Royal Thai Police Headquarters No. 606/2549.
http://www.immigration.go.th/nov2004/en ... p?page=act7.24 In the case of medical
treatment or
convalescence or to
look after a patient:
Permission will be
granted for a period of
not more than 90 days
at a time.
(1) Confirmation and request has
been made by a physician
responsible for the treatment.
(2) In the case of looking after a
patient, confirmation and
request has been made by the
physician responsible for the
treatment or by an embassy or
consulate.
(3) For non-family members of the
patient, permission shall be
granted to not more than one
person.
1. Application form
2. Copy of the applicant's passport
3. Confirmation letter and request
from the physician responsible
for the treatment
4. Only in the case of looking after
a patient, confirmation letter and
request from the physician
responsible for the treatment or
from the embassy/consulate
must be provided.