OBJECTIVES: Pharmacovigilance represents an important tool to support the maintenance of drug safety through evaluation of spontaneous adverse events (AE) reporting. AEs represent one important cause of morbidity and mortality worldwide when not managed correctly, being very frequent, especially during oncology treatments. However, underreported phenomenon occurs often due inefficient spontaneous reporting by patients, physicians and caregivers. Therefore, the aim of this survey was to evaluate the knowledge and perception related to pharmacovigilance in Brazil.  METHODS: From February to March 2015, 260 respondents answered an internet-based survey related to knowledge on pharmacovigilance from Oncoguia Institute, an independent nonprofit cancer advocacy institution. Descriptive analyses were performed according to answers frequency.  RESULTS: Among the respondents, 70.8% were diagnosed with cancer, of which breast cancer was the most frequent (58%) followed by colorectal cancer (4%). Reported treatment included chemotherapy (96%), surgery (84%), 48% radiotherapy (48%). Of all, 46% and 44% were treated by public and private health insurance, respectively. Most of the respondents were not aware of the importance of a pharmacovigilance AE report (52%). In fact, 21% of the respondents were not aware of what AEs are. In 66% of the cases, physicians have described the main AE expected to the prescribed treatment. Respondents reported nausea (80%), hair loss (77%), weight gain (49%) and vomiting (45%) as the most common AEs.  Only 7% and 4% of the respondents were aware that AEs could be reported to pharmaceutical industry and ANVISA, respectively. CONCLUSIONS: This survey demonstrates that knowledge and perception regarding AEs, such as definition, importance and how to proceed in case of having one, including the importance of pharmacovigilance system, are very reduced among common public, including cancer patients. Therefore, there is an enormous need for educational intervention regarding AEs reporting importance in general public, patients and physicians, especially in oncology.