Abstract Background Monkeypox is a zoonotic orthopoxvirus infection endemic in central and western Africa. In May 2022, human monkeypox infections including human-to-human transmission were reported in a multi-country outbreak in Europe and North America. Case presentations Here we present the first two cases of monkeypox infection in humans diagnosed in Germany. We present clinical and virological findings, including the detection of monkeypox virus DNA in blood and semen. The clinical presentation and medical history of our patients suggest close physical contact during sexual interactions as the route of infection. Conclusion Monkeypox requires rapid diagnosis and prompt public health response. The disease should be considered in the current situation especially the differential diagnosis of vesicular or pustular rash, particularly in patients with frequent sexual contacts. Most importantly, it is essential to raise awareness among all health professionals for the rapid and correct recognition and diagnosis of this disease, which is probably still underreported in Europe (Adler et al. in Lancet Infect Dis https://doi.org/10.1016/s1473-3099(22)00228-6, 2022).