AbstractBrazil is presently (2010) the second largest producer of Genetically Modified (GM) crops. The legal framework to support both research activities and the commercial release of Genetically Modified Organisms (GMOs) is, however, very recent, as the Biosafety Law dates back from 2005. After the indispensable risk analysis, done by National Technical Committee for Biosafety (CTNBio), a GM plant can be approved for commercial release. Nevertheless, as stated in the Normative Resolution nr. 5 (NR-5), 2008, the post-market monitoring is mandatory. However, the first GM crop in Brazil, the herbicide tolerant soybean, was harvested in 2005. The CTNBio asked, then, for a monitoring plan and the applicant designed a complex study focused on case-specific monitoring. After four years the detailed field studies proved that no harm derived from this crop. The costs, nevertheless, were enormous. In May 2010, 21 GM plants were already approved for commercial release in Brazil, corresponding to different events in soybean (6), cotton (8) and maize (9). Single and stacked events tolerant to herbicides or insect-resistant are presently been planted for all three crops. If, for each single event and for the stacks, a laborious post market monitoring plan were to be executed, the total costs would be unbearably high. The applicant, i.e. the seed company in the case of the three common crops, is legally responsible for the monitoring in Brazil. It is also responsible to produce an adequate monitoring plan. Since the rules in the Normative Resolution nr. 5 are far from being clear, the applicants either propose an elaborated plan for case-specific monitoring or, conversely, submit a very simple plan, targeting some potential adverse effect that can be more easily evaluated in commercial fields. All data generated must be reported to federal agencies belonging to at least three different ministries. Monitoring is also a responsibility of some federal agencies, as stated in the Biosafety Law, like registration and inspection agencies and other entities, which are responsible for, among other duties, keep updated information in the Biosafety Information Systems (SIB) of institutions and technical responsible individuals that carry out activities and projects related to GMOs and their by products. It is not clearly stated either in the Biosafety Law or in the NR-5 that monitoring should be split in case-specific monitoring and general surveillance, as adopted in Europe. If case-specific monitoring plans are difficult to design, a sensible suggestion for the general surveillance was not yet achieved. Nevertheless, the info-concentrating SIB may be a valuable source for the general surveillance, once it starts to operate. In conclusion, due to the lack of clear information about how to produce an adequate monitoring plan, stakeholders either tend to unnecessarily enlarge the monitoring scope or shorten it to a few objectives. The general surveillance is either not contemplated in the monitoring plans or minimally treated. It is important to keep in mind that the applicants are responsible to produce most of the data, even for the general surveillance, and this can be extremely difficult in a scenario where 20 or more different events are cultivated, frequently in neighboring fields. The EuropaBio approach to general surveillance for cultivation of GM crops (available from Nature Precedings "doi:10.1038/npre.2010.4451.1":http://dx.doi.org/10.1038/npre.2010.4451.1) is difficult to be largely adopted: farmers may be unable to meaningfully answer the questionnaire and the network has a very restricted number of potential participants. CTNBio is aware of these challenges and has already started to adjust the NR-5 to better guide the applicants in their writing of monitoring plans.