Lofgren’s syndrome is characterized by a clinical triad of associated erythema nodosum, bilateral hilar lymphadenopathy and arthritis. This syndrome has usually been considered a specific form of sarcoidosis. We recently observed a case of characteristic Lofgren’s syndrome in a patient who presented simultaneously with urethritis due to Ureaplasma urealyticum. To the best of our knowledge, this report represents the first case of Lofgren’s syndrome in association with U. urealyticum. A 32-year-old man, with no notable medical history, was admitted to hospital with a 10-day history of periarticular ankle inflammation associated with fever of 38°C and dysuria without urethral discharge of 2 days’ duration. On physical examination, the patient appeared well. His temperature was 37.7°C, pulse was 80 beats per minute, blood pressure was 130/80 mmHg and respiratory rate was 16 breaths per minute. No lymphadenopathy, parotid enlargement or anterior uveitis were noted. Lung, heart, abdomen and neurologic examinations were normal. Bilateral periarticular ankle inflammation (swelling of both ankles with acute inflammatory signs and preserved articular motion) and erythematous nodules and plaques involving the anterior part of the calf were observed on both legs. The hematocrit, leukocyte and platelet values were normal. The erythrocyte sedimentation rate was 88 mm/h. The aspartate aminotransferase (104 U/l), alanine aminotransferase (187 U/l) and alkaline phosphatase (373 U/l) levels were elevated. The levels of urea, creatinine, calcium, protein electrophoresis and all other routine blood chemical values were normal. Urinalysis was positive for leukocyte esterase, and multiple leukocytes were seen on microscopic examination of urine. Urine culture was negative. A Gram stain of the urethral smear showed polymorphonuclear neutrophils, but no typical intracellular gram-negative diplococci, while tissue culture grew U. urealyticum. A blood culture and a tuberculin skin test with 5 units of PPD were negative. Viral and bacterial serologic studies were negative for Brucella spp., Salmonella spp., Yersinia enterocolitica, hepatitis B surface antigen, hepatitis C, syphilis and HIV. Autoantibody screening was also negative for nuclear and DNA antibodies. Tests for rheumatoid factor and HLA-B27 antigen were negative, and complement levels were normal. The angiotensin-converting enzyme level was 46.8 U/l (normal range 7.8–51.6). A chest radiograph revealed bilateral hilar adenopathy without parenchymal infiltration. A thoracic computed tomography scan showed multiple mediastinal lymph nodes up to 1 cm and bilateral hilar lymphadenopathy. A gallium-67 lung scan showed a pattern of uptake enlarged nodes in the paratracheal and mediastinal regions. Pulmonary function tests showed evidence of minimal airflow limitation. A biopsy of skin nodules was indicative of erythema nodosum. The patient was treated successfully with doxycycline, 100 mg twice daily for 10 days, and both cutaneous and articular manifestations healed completely within 3 weeks. At 1-year follow-up the patient remained without symptoms, and repeat angiotensin-converting enzyme measurement, chest radiograph and thoracic computed tomography were normal. U. urealyticum is probably the most frequent cause of non-chlamydial non-gonococcal urethritis, although its role as a pathogen has been controversial. It clearly causes symptomatic urethral infection, but it has also been found to colonize as many as 60% of asymptomatic men attending sexually transmitted disease clinics [1]. With regard to extragenital infections, sexually acquired reacM. Lopez-Gomez (*) . M. A. Lopez-Ruz . J. Jimenez-Alonso Section of Infectious Diseases, Service of Internal Medicine, Hospital Universitario “Virgen de las Nieves”, Avenida Fuerzas Armadas 2, 18004 Granada, Spain e-mail: mlopezg@fundacionhvn.org Tel.: +34-95-8157687 Fax: +34-95-8020494