Dionysia specializes in Antitrust & Competition Law, both Greek and European. Between 2001 and 2018 she worked for the Hellenic Competition Commission in various positions including two full terms as Director General of the HCC. During her tenures, she supervised HCC investigations drafting the legal assessment in various Statements of Objections, the views of the HCC in support of its decisions before the Courts, and legal opinions. She has also carried out unannounced inspections (dawn raids). She represented the HCC at the highest executive level in such international fora such as the European Competition Network (ECN), the Organization for Economic Co-operations and Development (OECD), and the International Competition Network (ICN). Dionysia has also been member-delegate of the ECN Executive Committee and the OECD Competition Committee.

She has participated in several Law Drafting Committees and represented the HCC in the presentation of its Annual Report at the Special Permanent Committee of Institutions and Transparency of the Hellenic Parliament. She co-chaired the EU Council’s negotiation team for the adoption of the new Directive on Private Damages for infringements of competition law in the context of the Greek Presidency of the EU (A’ semester 2014). She has also participated as National Expert in the Council negotiation team for the adoption of the new Directive for the enforcement of European National Competition Authorities (ECN).

Dionysia has advised companies in the construction, gas, and retail sectors.