Various infectious diseases are transferable from animal to man (zoonosis). Some of these, such as rabies and leptospirosis are severe, while others pass relatively mild. In zoological litterature these diseases and preventive measures against contamination are rarely described. The occurence of such infections among staff members of natural history museums is often due to carelessness and ignorance. Especially when collecting in the (sub )tropics, one takes a serious risk of getting infected. In this paper five zoonoses (Lyme disease, Rabies, Aspergillosis, Leptospirosis, Psittacosis/Omithosis) are described, including the natural history of the disease, geographical distribution, hosts, treatment, and consequences for staff members of natural history museums.