A new outbreak of monkeypox virus (MPXV) infection, a zoonotic infection endemic in Central and West Africa, is spreading throughout the world with new epidemiology and clinical features. Our aim was to characterize patients presenting to Dermatology emergency room with a MPXV infection between 15 May and 30 June 2022 in a tertiary hospital in Madrid, Spain. We collected 53 patients and describe their clinical, demographic and epidemiological characteristics and followed their evolution. Most of the patients were men who had sex with men with high-risk sexual practices and no recent travels abroad. Most of them (91%) had had a sexually transmitted infection before. All patients had typical skin lesions consisting of vesicular-pustular rash with central umbilication which was localized or disseminated. The most frequent extracutaneous symptoms were fever, painful regional lymphadenopathy and asthenia. Proctitis was present in more than one third of patients. All patients were diagnosed by real time polymerase chain reaction of samples obtained from skin lesions. Pharyngeal and/or rectal exudates demonstrated MPXV in 74% of patients. The current worldwide outbreak of MPXV infections shows epidemiological and clinical differences from previous ones. Clinicians should be aware of these characteristics to correctly diagnose this emerging disease.