BackgroundHealth Canada posts the outcomes of all New Drug Submissions. In some cases, companies have withdrawn submissions or submissions have been rejected by Health Canada for new active substances (NAS). This study explores the reasons for those decisions and compares them with decisions made by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA).MethodsThis is a cross-sectional analysis. Submissions for NAS between December 2015 and December 2022 were identified along with the original indications for the NAS, the information that Health Canada had available and the reasons for its decisions. Similar information was sourced from the FDA and the EMA. Their decisions were compared to those made by Health Canada. The time between decisions by Health Canada, the FDA and the EMA were calculated in months.ResultsHealth Canada considered 272 NAS and approved 257. Sponsors withdrew 14 submissions for 13 NAS and Health Canada rejected submissions for 2 NAS. The FDA approved 7 of these NAS and the EMA approved 6, rejected 2 and submissions were withdrawn by 2 companies. Health Canada and the FDA considered similar information in 4 of 7 cases. Indications were the same except in one case. The FDA made decisions a mean of 15.5 months (interquartile range 11.4, 68.2) before companies withdrew their submissions from Health Canada. There were 5 cases where Health Canada and the EMA considered the same information and in 2 of those the outcome was different. Health Canada and EMA decisions were generally made within 1–2 months of each other. Indications were the same in all cases.ConclusionsDifferences in decision making by regulators are due to more than the data which with they are presented, the timing of the presentations and the indications for the drugs. Regulatory culture may have influenced decision making.