We have conjugated S,S′-bis-trityl-N-BOC-N′-acetic acid-1,2-ethylenedicysteamine, a protected bis-amino-bis-thiol (BAT) tetraligand, with 2-(4′-aminophenyl)-1,3-benzothiazole, a derivative of thioflavin-T with known affinity for amyloid. The conjugate was efficiently labelled with 99m Tc by heating of the protected precursor in diluted hydrochloric acid followed by neutralization and heating in the presence of 99m Tc-tartrate. It was demonstrated that the 99m Tc-BAT-phenylbenzothiazole conjugate binds in vitro to amyloid β present in postmortem brain slices of Alzheimer’s patients. Despite its high lipophilicity and neutral character, the radiolabelled conjugate did not cross the blood–brain barrier to a sufficient degree and therefore is not useful for detection of Alzheimer’s disease. Further evaluation of this 99m Tc-labelled tracer agent could elucidate its potential usefulness to visualize amyloid plaques in peripheral amyloidosis.