Despite technological advances in management, health and genetics applied to poultry farming worldwide, there is still a high rate of detection of pathologies and technopathies at slaughterhouses, resulting in losses for the poultry production chain. Thus, this work aimed to evaluate the condemnation occurrence index (COI) and adjusted seasonal index (ASI) of poultry between 2009–2019, in an export slaughterhouse in southeastern Brazil. Data were obtained from official spreadsheets from the Brazilian Federal Inspection Service (FIS) and used to calculate the COI, correlation analysis between the main causes of condemnation, and ASI assessments throughout the year. Seven percent (55,594,318) of the carcasses were condemned (partial or total), and the most frequent causes, contamination and contusion/traumatic injury, amounted to 63.5% of the total condemnation. There was a trend of increasing condemnation throughout the time series evaluated, with COI varying between 45,282–149,809 condemnations per 1,000,000 poultry slaughtered. Evaluating the ASI, it was identified that for ascitic syndrome, July has a higher index value (1.63) than the months between January–June (P < 0.05). It was concluded that the main causes of condemnation were mainly related to failures in pre-slaughter and slaughter management. Analysis of condemnation history, demonstrated by ASI, can provide subsidies for preventive measures and optimization of human and financial resources, generating positive impacts on food safety, productivity, and profitability of the sector.