Many men presenting with epididymo-orchitis in general practice are being prescribed antibiotics but not undergoing investigation, a large UK study has found. Information from the General Practice Research Database (GPRD), which contains anonymised longitudinal patient records from 460 general practices, was used to estimate the incidence of epididymo-orchitis in primary care between 2003 and 2008 and examine the management of patients with this condition. Men aged 15-60 years presenting with a first episode of epididymo-orchitis between 30th June 2003 and 30th June 2008 were included. Aspects of management assessed included: testing for STIs or UTIs, treatment using specific antibiotics for epididymo-orchitis, evidence of referral for further care or management only within the practice. A total of 12,615 patients, median age 37 years, with a first episode of epididymo-orchitis were identified. The incidence was highest in 2004-2005 and declined in the later years of the study. The fall in incidence coincided with the roll out of the National Chlamydia Screening Programme but a causal link cannot be substantiated by this study. 'The incidence of acute epididymitis, with or without testicular involvement, is estimated to be around 40/10,000 person years in the UK. In men under 35, the likely pathogen is an STI such as chlamydia or gonorrhoea; in older men, this is likely to be due to non-sexually transmitted infections. Just under half of cases may have no identifiable cause. Effective treatment is important to avoid complications such as infertility, prostatitis and urethral strictures. Cases related to STIs present opportunities for partner notification.'