Mycoplasma genitalium infection contributes to 10–35% of non-chlamydial non-gonococcal urethritis in men. In women, M. genitalium is associated with cervicitis and pelvic inflammatory disease (PID). Transmission of M. genitalium occurs through direct mucosal contact. Asymptomatic infections are frequent. In women, symptoms include vaginal discharge, dysuria or symptoms of PID – abdominal pain and dyspareunia. In men, urethritis, dysuria and discharge predominates. Besides symptoms, indication for laboratory test is a high-risk sexual behaviour. Diagnosis is achievable only through nucleic acid amplification testing (NAAT). If available, NAAT diagnosis should be followed with an assay for macrolide resistance. Therapy for M. genitalium is indicated if M. genitalium is detected or on an epidemiological basis. Doxycycline has a low cure rate of 30–40%, but does not increase resistance. Azithromycin has a cure rate of 85–95% in macrolide susceptible infections. An extended course appears to have a higher cure rate. An increasing prevalence of macrolide resistance, most likely due to widespread use of azithromycin 1 g single dose without test of cure, is drastically decreasing the cure rate. Moxifloxacin can be used as second-line therapy, but resistance is increasing. Uncomplicated M. genitalium infection should be treated with azithromycin 500 mg on day one, then 250 mg on days 2–5 (oral), or josamycin 500 mg three times daily for 10 days (oral). Second line treatment and treatment for uncomplicated macrolide resistant M. genitalium infection is moxifloxacin 400 mg od for 7–10 days (oral). For third line treatment of persistent M. genitalium infection after azithromycin and moxifloxacin doxycycline 100 mg two times daily for 14 days can be tried and may cure 30%. Pristinamycin 1 g four times daily for 10 days (oral) has a cure rate of app. 90%. Complicated M. genitalium infection (PID, epididymitis) is treated with moxifloxacin 400 mg od for 14 days. Received: 3 March 2016; Accepted: 23 June 2016 Conflicts of interest None declared. Funding sources None declared. Introduction Mycoplasmas are the smallest free-living microorganisms. In the urogenital tract, the relevant species areM. genitalium, Ureaplasma urealyticum, U. parvum and M. hominis. M. hominis and the ureaplasmas will not be dealt with in the present guideline. Mycoplasma genitalium was first isolated in 1980. M. genitalium infection is unequivocally associated with male NGU and even stronger associated with non-chlamydial non-gonococcal urethritis (NCNGU). The prevalence of M. genitalium in men with NCNGU ranges from 10% to 35%, thus contributing significantly to the overall burden of disease. In comparison, M. genitalium is detected in only 1% to 3.3% of men and women in the general population. In women, several studies have demonstrated the association between M. genitalium and urethritis, cervicitis, endometritis, and pelvic inflammatory disease (PID). In a recent meta-analysis, significant associations were found between M. genitalium and cervicitis [pooled odds ratio (OR) 1.66], and PID (pooled OR 2.14).M. genitalium has been associated with preterm birth (pooled OR 1.89), and spontaneous abortion (pooled OR 1.82), but the prevalence of © 2016 European Academy of Dermatology and Venereology JEADV 2016 DOI: 10.1111/jdv.13849 JEADV