Aim: Penicillin allergy accounts for the majority of all reported adverse drug reactions in adults and children. Foregoing first-line antibiotic therapy due to penicillin allergy label is associated with an increased prevalence of infections by resistant organisms and longer hospitalisation. Clinician awareness of allergy assessment, referral indications, management of allergy and anaphylaxis is therefore vital but globally lacking. We aim to assess the knowledge of penicillin allergy, assessment and management in Western Australian health professionals. Methods: An anonymous survey was distributed to pharmacists, nurses and physicians within Western Australian paediatric and adult Hospitals, Community and General Practice. Results: In total, 487/611 were completed and included in the statistical analysis. Only 62% (301/487) of respondents routinely assessed for patient medication allergies. Of those who assessed allergy, 9% (28/301) of respondents met the Australian standards for allergy assessment. Only 22% (106/487) of participants correctly cited all indications for management with adrenaline in anaphylaxis to antibiotics and 67% (197/292) of physicians rarely or never referred to an allergy service. Paediatric clinicians had an increased understanding of allergy assessment and anaphylaxis management. Recent penicillin allergy education within a 5-year period led to significant improvements in allergy knowledge. Conclusion: Overall, knowledge, assessment and management of penicillin allergies among practitioners in Western Australia are currently inadequate in adults and paediatric clinicians to provide safe and effective clinical care. The implementation of a targeted education program for WA health professionals is urgently required and is expected to improve clinician knowledge and aid standardised penicillin assessment (de-labelling) practices.