Contract research organizations (CROs) provide services to the life science industries along product development. There are more than 2000 CROs operating worldwide, representing revenues of more than $20 billion. One distinguishes between "Product" and "Patient" CROs. Whereas the production sites of CMOs are multipurpose plants, allowing for the production of tens to hundreds of tons of fine chemicals, the work places of patient CROs are the test persons (volunteers) for the clinical trials and those of the product CROs are the laboratory benches. Major customers for CRO services are the large global pharmaceutical companies. Half a dozen companies (Pfizer, GlaxoSmithKline, Sanofi-Aventis, AstraZeneca, Johnson & Johnson, and Merck & Co.) alone absorb about one third of all CRO spending. As for CMOs also for CROs, biotech start-up companies with their dichotomy between ambitious drug development programs and limited resources are the second most promising prospects. Product CROs (chemical CROs) are providing primarily sample preparation, process research and development services. An overlap between the latter and CMOs exists with regard to pilot plants (100 kg quantities), which are part of the arsenal of both types of enterprise.
There are more 100 product CROs. Most of them are privately held and have revenues of $10–$20 million per year or less, adding up to a total business in the range of $1.5-$2 billion. Their tasks are described in Chapter 5,
Examples of are:
*In North America: Alphora; Delmar; NAEJA, all Canada. AMRI; Aptuit; Cambridge Major; ChemBridge; Innocentive; Irix Pharmaceuticals, PharmEco, all USA.
*In Europe; Carbogen-Amcis, Switzerland; Chemcomm, Germany; ChemDiv, Russia; Clauson-Kaas, Denmark; Enamine Ltd, Ukraine; Girindus, Germany; Nerviano Medical Sciences, Italy; Recipharm, Sweden; Serichim, Italy; Solvias, Switzerland, Netherlands.
*In Asia: BioDuro, Medicilon, Pharmaron; WuXi AppTec, all China; Acoris; Aptuit Laurus; Biocon / Syngene; Chembiotek; Chempartner; ProCitius,  all India; NARD Institute, Riken, both Japan.
The business of CROs is usually done through a "pay for service" arrangement. Contrary to manufacturing companies, invoicing of CROs is not based on unit product price, but on full-time equivalents (FTEs), that is, the cost of a scientist working one year on a given customer assignment. 
Companies offering both contract research and manufacturing services (CRAMS) combine the activities of CROs and CMOs. Their history is either a forward integration of a CRO, which adds industrial scale capabilities or backwards integration of a CMO. As there are only limited synergies (e.g. > 90% of the projects end at the sample preparation stage). It is questionable, though, whether one-stop shops really fulfil a need. Actually, the large fine chemical companies consider the preparation of samples more as marketing tool (and expense ...) rather than a profit contributor.
The offerings of Patient CROs (Clinical CROs) comprise more than 30 tasks addressing the clinical part of pharmaceutical development at the interface between drugs, physicians, hospitals, and patients, such as the clinical development and selection of lead new drug compounds. As clinical trials represent the largest expense in pharmaceutical research, the market for patient CROs is larger than for their product counterparts. Thus, the sales of the top tier firms, Charles River Laboratories, Covance, Parexel, PPD, Quintiles Transnational, all USA, and TCG Lifescience, India; are in the $1–$2 billion range, whereas the largest product CROs have revenues of a few 100 million dollars.