A young man presented with systemic upset and generalised lymphadenopathy. Later, it transpired that he was under investigation for a scrotal mass. Investigations were carried out to ascertain the cause of his symptoms including lymph node biopsy. Because of the presence of a scrotal mass in a sexually active male, a urinary Chlamydia ligase chain reaction (LCR) test was carried out. The result was positive and he was treated with doxycycline for 2 weeks. His symptoms settled and further, the urinary LCR was negative. We propose that Chlamydia trachomatis infection caused his illness and that urine PCR or LCR tests for Chlamydia is a convenient and useful investigation in sexually active males with generalised lymphadenopathy and fever of unknown origin.