Motor Man

I am considering sponsoring m,y sister from UK aged 73 . My ? is if I
agree and sign the affidavit will I be held responsible for hospital
and medical bills for her possible medical care in the future. She has
enough resources, pension etc to live on OK, but the medical scene
scares me . Any advice please.

nettlebed

No. Private debt she incurs will be her personal responsibility. You are just saying that she will not become a public charge. Your obligations, as defined in I-864 are:

The person completing this affidavit is the sponsor. A
sponsor's obligation continues until the sponsored immigrant
becomes a U.S. citizen, can be credited with 40 qualifying
quarters of work, departs the United States permanently, or
dies. Divorce does not terminate the obligation. By signing
this form, you, the sponsor, agree to support the intending
immigrant and any spouse and/or children immigrating with him
or her and to reimburse any government agency or private
entity that provides these sponsored immigrants with Federal,
State, or local means-tested public benefits.

You can find the PDF of the I-864 at:

http://uscis.gov/graphics/formsfee/f...iles/I-864.pdf

Incidentally, the current waiting time for siblings sponsored by USCs is around 12-14 years. You are a USC, aren't you? Green Card holders may not sponsor
siblings. See section 2 of:

http://uscis.gov/graphics/formsfee/f...iles/i-130.pdf