These range from reconstructing an elaborate fraud scheme to trace back stolen EU funds in a €1.7bn transport project to recommending the recovery of €26.7m defrauded by a criminal gang.
In these and other cases, OLAF's annual report says its investigators "put their skills to work for the benefit of EU taxpayers."
The report, published at a news conference in Brussels on Wednesday, said that by shedding light on elaborate cross-border fraud patterns, and coordinating with national and EU authorities to bring fraudsters to justice, OLAF "made an important contribution to ensuring EU funds can reach the citizens who need them the most."
The report says that, in 2016, the Brussels-based agency concluded 272 cases, and opened 219 new investigations, a high caseload managed against the backdrop of a constant staff decrease.
It issued 346 recommendations to the relevant member state and EU authorities, which will enable the recovery of €631m to the EU budget, and help bring fraudsters to justice.
It succeeded in reducing the duration of its investigations, which were concluded in an average of 18.9 months, a new record for the office.
Its mandate allows OLAF to have a complete picture of the changing nature of fraud with EU funds. Using information gathered through its investigations, OLAF analysed the most striking trends in fraud, in an empirical study into how criminals have adapted to the new economic and regulatory landscape, constantly coming up with novel and creative ways to try to pocket EU money.
According to the report, OLAF's 2016 found that public procurement is still an attractive marketplace for fraudsters, who use corruption and offshore accounts as fraud facilitators. Many procurement fraud cases are transnational, as the new fraud scenarios often involve a contracting authority from one member state and bidders from several other member states who subcontract their works to companies again located in different countries.
Research and employment grants constitute a lucrative fraud business, with double-funding and employment subsidy fraud becoming increasingly popular.
Criminal networks use complex transnational schemes to evade customs duties.
The nature of cigarette smuggling has significantly changed in the past years, with smugglers turning their attention to trafficking 'cheap whites', or non-branded cigarettes.
In the past years, OLAF has, said the report, significantly invested in the most innovative investigative techniques and tools. This helped it acquire state-of-the-art forensic and analytical tools, which help keep it at the "forefront of the global fight against fraud."
In 2016, OLAF's report said the agency used these tools, among others, to analyse the Panama Papers, which led to the office opening a number of investigations.
The agency, said the annual report, is also at the forefront of negotiating legislative texts concerning the protection of the EU's financial interests against fraud and corruption. In 2016, progress was made on two important policy initiatives where OLAF had an active role.
In one case, it was decided that serious VAT offences, involving a damage of at least €10m, would be included in the scope of the directive on the fight against fraud to the Union's financial interests by means of criminal law (so-called 'PIF directive').
"At the same time, it became clear that, in the absence of unanimity, the European Public Prosecutor's Office (EPPO) would be established under an enhanced cooperation procedure," says the report.
"OLAF and EPPO will work closely together to ensure that fraudsters are not only identified, but effectively brought to justice," it adds.
While OLAF is a modern investigative body, able to solve even the most complex, cross-border fraud cases, OLAF's Director-General Giovanni Kessler argued that the tools granted to it need to be updated in order for the Office to adapt to the current fraud landscape.
Speaking on Wednesday, the Italian said, "In my view, the future should be guided by reform. As anti-fraud investigators, we need the right tools to look into possibly illicit financial flows, to follow the money throughout the fraudulent chain, as well as to have clear access to the premises of economic operators or institutions that may have been involved in fraudulent activities."
Entering the last year of his mandate, Kessler - who was a controversial appointment - pointed out that OLAF has achieved "excellent results in complete independence", with a staff "fully dedicated to working for the benefit of the European citizens, and supported by a cohesive team of managers who have revitalised the work of the Office."
In the past, OLAF has been dismissed as being ineffective in the fight against fraud.
But Kessler told reporters, "Looking towards the future, I am genuinely confident about what's in store for the Office."