In brief
A contract research organisation (CRO) performs tasks on behalf of a sponsor in the planning, conduct and analysis of clinical trials. Under the EU Clinical Trials Regulation, the sponsor is whoever takes responsibility for the initiation, management and financing of a trial. In practice this is usually the pharmaceutical or biotechnology company that wants to test its medicinal product in humans.
Clinical trials are usually divided into phases. In Phase I an active substance is given to humans for the first time, depending on the medicinal product to healthy volunteers or to selected patients, for example in oncology. The focus is on safety, tolerability and the behaviour of the substance in the body. Phase II examines efficacy and the appropriate dose in patients, Phase III confirms efficacy and safety in a larger number of patients as the basis for marketing authorisation, and Phase IV covers trials with medicinal products that are already authorised. A CRO can work in any of these phases, and many providers specialise in certain phases or therapeutic areas.
When you need this
Many small and medium-sized companies do not permanently keep in house all the specialist functions a clinical trial requires. This becomes particularly clear before the first trial: the application has to be prepared, trial sites have to be found and contracted, and data have to be collected and analysed, all under rules the team has had little to do with so far. A CRO brings experience and established processes here.
Larger companies also work with CROs, for example when several trials run at the same time, when trial sites are needed in countries where they have no organisation of their own, or when capacity is lacking for individual tasks such as biostatistics or medical writing. A sponsor that is not established in the EU must, as a rule, also appoint a legal representative in the Union, through whom communication with the authorities takes place. Member States may waive this for certain trials and accept a contact person in their country instead. Service providers often take on this role as well.
Legal basis and rules
Clinical investigations of medical devices are subject to different rules, mainly the Medical Device Regulation (EU) 2017/745. Non-interventional studies do not fall under Regulation 536/2014. These are studies in which treatment follows normal clinical practice, that is, it is not determined in advance by the protocol and no additional diagnostic or monitoring procedures are added.
How the work is organised
What a CRO can do for you essentially follows the course of a trial. The following services are often offered individually or as a package:
In principle, you can choose between two models. With full service, a CRO takes on the trial almost entirely and you steer it through a dedicated contact person. This relieves your own team but makes you more dependent on one provider. With functional outsourcing, you contract out only monitoring or only biostatistics, for example, and keep project management yourself. This gives you more control but requires you to manage the interfaces between several service providers yourself.
In both cases, as sponsor you are responsible for checking the provider’s suitability before delegating tasks to it. Many sponsors use an audit for this. This is followed by a contract that states exactly which tasks are transferred and which remain with you. During the trial, regular reports, agreed key figures and a clear escalation path for problems are part of the arrangement. Sponsor and investigator each keep the essential documents in a Trial Master File, and it should be clear from the start who maintains it and how you can access it at any time.
What to look for when choosing a provider
Whether a CRO suits your trial depends less on its size than on its experience, its access to trial sites and the way it assures quality. The following questions help when comparing several offers:
Frequently asked questions
Do I remain responsible as sponsor if the CRO takes on everything? +
What must the contract with the CRO contain? +
Is a small specialised CRO worse than a large one? +
Does the CRO also manufacture the investigational medicinal products? +
Sources
Every statement in this text was checked against these primary sources (as of 10.11.2026). Laws, guidelines and authority websites, no advertising.
- EUR-Lex (EU-Recht) · oj
- ICH · E8-R1_Guideline_Step4_2021_1006.pdf
- EMA · clinical-trials-transition-new-eu-system-one-year-left
- Gesetze im Internet · __77.html
- Gesetze im Internet · __40.html
- ICH · ICH_E6(R3)_Step4_FinalGuideline_2025_0106.pdf
- EMA · ich-e6-good-clinical-practice-scientific-guideline
- EUR-Lex (EU-Recht) · oj