The occurrence of a history of clinical Lyme borreliosis and the prevalence of positive antibodies to Borrelia burgdorferi were studied in 431 Dutch hunters. The majority of the hunters (336 or 78%) did not report any complaints and had no positive IgG antibodies to B. burgdorferi. Sixty-five hunters (15.1%) had no clinical manifestations but did not have positive antibodies to B. burgdorferi. Only 1.9% of the population studied had had past symptoms of definite or probable Lyme borreliosis. Likelihood ratios were high (21.3) for the recognition of erythema migrans, but much lower for tick bites (3.6) or positive IgG Lyme serology (3.5). Clinical history turned out to be a more powerful diagnostic tool than Lyme serology.