Novel propanoic acid derivatives are integrin receptor antagonists or inhibitors, in particular of the avb3 integrin receptor. The compounds of the invention are for instance useful for the treatment of solid tumors by inhibition of angiogenic growth of tumor vessel network, thus promoting tumor regression, inhibition of metastatic spread, thus avoiding cancer metastases, inhibition of bone resorption, thus controlling osteoporosis, inhibition of smooth muscle cells migration into neointima, thus blocking restenosis after percutaneous coronary angioplasty and the treatment of other pathological conditions mediated by cell adhesion, cell migration or angiogenesis such e.g. diabetic retinopaty, rheumatoid arthritis and inflammation.