Pet animals i.e. vertebrates from fish to mammals are often suspected to transmit germs of various systematic position (viruses, bacteria, fungi and parasites) to human beings. A critical analysis shows that only a very limited number of such organisms can be transmitted from animals to man. Zooanthroponoses with pet animal origin is a very rare phenomenon. Bacteria like salmonellae which were incriminated to be the cause of about 250,000 infections of man per year, particularly of children, in the USA in the early 70th have really no importance in the Federal Republic of Germany. The statistical dates published every year by the "Statistisches Bundesamt" show clearly that only about 1 case in a year can be traced backwards to reptiles in spite of about 50,000 registered cases of human salmonellosis per year. If we compare the number of about 1 million of reptiles in captivity the incidence is very low. Similar relations exist for other germs, too. As an example the choriomeningitis of golden hamsters is often mentioned. In newspapers and other popular publications this infection is said to be extremely dangerous for children but in reality only a few cases were registered years ago. Nowadays precautions in the breeding farms etc. make it very unlikely that such virus transmissions have any practical importance. This situation is comparable with mycosis caused by fungi like Trichophyton which have their origin in certain mammals. Also psittacosis--in form r times not infrequently the cause of sickness and death in man--nowadays is only found sporadically in man, in spite of about the same number of cases in parakeets and other birds. The terrible risk of the disease can be prevented since tetracycline therapy is a successful treatment. It can be stated that zooanthroponoses which have their origin in pet animals is a very rare manifestation, but often misinterpretations are given either ignoring the knowledge of a certain infection or fishing for publicity! One of such examples is toxoplasmosis. About 15 years after the discovery of the life cycle of the protozoon Toxoplasma gondii and the experimentally proven fact that oocysts can be produced only in cats, and therefore transmission to humans is only possible with these stages other animals like rabbits or guinea pigs are still incriminated as the cause of human infections. Apart from the discussed problems and the possibility of transmission of infectious agents from animals to man we must also take into consideration the positive psychological aspects of animal keeping for the hobbyist, and particularly for children.(ABSTRACT TRUNCATED AT 400 WORDS)