Betalactams are the most commonly prescribed antibiotics Antibiotics worldwide. Suspected allergic reactions to Betalactams are often reported in patients, but only a minority of these reactions results from real immunological mechanism. Here we present our experience in allergological investigation of Betalactam reactions in Tishreen University hospital in Lattakia. To confirm or rule out the suspected diagnosis, Skin tests (pricks and Intradermal tests with PPL (Penicilloyl-polylysine), MDM (minor determinants) and soluble Betalactams) were performed in 20 patients reporting one reaction or more to Betalactam antibiotics. Oral provocation tests (OPT) were performed in patients with negative skin tests. Our results showed that Skin tests to PPL, MDM and Betalactams were positive in only two patients. The OPT confirmed our results as they were positive in those two positive skin tests patients(allergy to Clavulanic acid).Moreover, these results suggest that the diagnostic and predictivevalue of skin teststo Betalactam antibiotics is good, as no positive OPT was observed in patients with negative skin tests. In conclusion, suspected allergic reactions to Betalactam antibioticsremain a relevantproblem due to the need ofthese wide variety of drugs. This is the first study in Syria to date on immediate allergic reactions to Betalactam antibiotics and it showed the necessity to performed skin tests in suspected patients.