While immigration is unlikely to affect the employment of native workers in the long run, employment of immigrants may be associated with significant short-run adjustment costs for native workers as they have to fi nd alternative employment or are temporarily pushed into unemployment. In this paper, we therefore study the impact of immigrants at the workplace on the employment of native co-workers using a rich matched worker-fi rm data set for Denmark. Estimation of a single risk duration model for job spells of native workers shows that job separation rates increase if more immigrants are hired, especially when it comes to immigrants from Eastern Europe and less developed countries (LDCs). Furthermore, in a competing risks duration model, we fi nd that while immigrants from LDCs increase the unemployment risk for native workers, immigrants from Eastern Europe instead increase the job change probability of native workers. Thus, adjustment costs for native workers are more likely in the case where LDC immigrants are hired. Finally, we fi nd that the results only apply for low-skilled native workers