Integrin receptor antagonists whose molecular structure includes a tetrahydropyridimidinylaminoethyloxybenzoyl group on a sulfonylamino-.beta.-alanine nucleus exhibit increased binding affinity for the .alpha.v.beta.3 receptor when further substituted on the sulfonyl moiety with an N-amino alkycarbamyl group or a butyloxycarbonylamino alkylcarbamoyl group or similar groups.