Leptospirosis is a zoonotic infection caused by slow-growing spirochetes of the genus Leptospira. The clinical picture varies from asymptomatic disease and mild flu-like symptoms to severe infection with jaundice, renal failure and pulmonary haemorrhage (Weil's disease). Brown rats are the most important reservoir for human infection, and the animals excrete the bacteria in their urine. Humans are infected either through direct contact with infected animals or indirectly through contaminated fresh water and soil via wounds, damaged skin or mucous membranes. Here we present two cases of indigenous leptospirosis in Sweden, one of whom developed Weil's disease.