Honeybee colonies were studied at various locations in the Black Forest (SW Germany) during a honeydew flow from Abies alba. The mineral contents of honey samples and of bees from colonies affected by 'Waldtrachtkrankheit' were compared with those of honey and bees from healthy colonies. Honeydew honeys contained more potassium and phosphorus, and less sodium, than nectar honeys. Honey samples from affected colonies had significantly higher potassium and phosphorus contents, and a lower sodium content, than honeys from healthy colonies. During a strong honeydew flow, potassium and phosphorus contents in bee abdomens increased; the nitrogen content was unchanged, and sodium and calcium decreased. However, feeding experiments on healthy colonies indicated that the high mineral content of honeydew honeys is not the only cause of 'Waldtrachtkrankheit'.P. Walker.