A serum albumin binding antibody or fragment thereof comprising a heavy chain variable domain having the sequence given in SEQ ID NO: 1 or SEQ ID NO:2 and/or comprising a light chain variable domain having the sequence given in SEQ ID NO:3 or SEQ ID NO:4, in particular comprising a heavy chain variable domain and a light chain variable domain having the sequence given in SEQ ID NO: 1 and SEQ ID NO:3 or a heavy chain variable domain and a light chain variable domain having the sequence given in SEQ ID NO: 2 and SEQ ID NO:4. The disclosure also extends to polynucleotides encoding the antibodies or fragments, vectors comprising same and host cells capable of expressing the polynucleotides. The disclosure further includes pharmaceutical compositions comprising the antibodies or fragments and therapeutic used of any one of the same.