question: OBJECTIVE: The mobility of workers to other countries in a globalized work world has posed an added risk in the current pandemy of COVID-19 and can carry with it an increased risk of spread and transmission of the disease. The collaboration of the Occupational Health Units of the companies and the Health Authorities has been fundamental in the investigation of COVID-19 outbreaks secondary to international travel of workers on mission. The objective of this study was to describe the process of detection and follow-up of cases in an outbreak of COVID-19 in repatriated workers after a six-month mission in a factory of aircraft components in Poland. METHODS: A case series study was conducted. Data on sociodemographic, epidemiological and clinical course variables of the cases were collected by telephone clinical interview. Descriptive statistics were used to summarize the data. RESULTS: The outbreak involved 20 workers who shared the workplace and made the repatriation trip together. The outbreak investigation was initiated after detecting that a worker presented symptoms compatible with COVID-19 during the 4 days prior to the return trip, which was later confirmed by PCR. During follow-up, 40% (n=8) of the workers were considered cases confirmed by PCR. Of these, only 62.5% (n=5) presented symptoms. Fifty percent (n=4) had fever, 25% (n=2) had cough, respiratory distress, general malaise, and diarrhea, and 12.5% (n=1) had anosmia, ageusia, and conjunctivitis. All of them underwent home isolation with outpatient telephone follow-up. At the end of the follow-up, all were asymptomatic and returned to work. The mean close contact was 1.85 per case within the group (SD=3.13), with a range of 0-11, occurring primarily during attendance at extra work social events that were limited to members of the workers' own group and/or during the return flight. The health authorities were informed through established channels so that they could proceed with the detection and tracking of close contacts with people outside the group of workers that occurred during the flight and after arrival to Spain. CONCLUSIONS: Early detection of potential cases of COVID-19 with transmission capacity by the Occupational Health and Safety Departments of the companies, in collaboration with the Health Authorities, is essential for more efficient case and contact management of imported cases of COVID-19.