The aim of the presented study was the investigation of a probable influence of social stress on spontaneous amyloidosis. As stress-inducing parameter crowding of the animals was used. 220 Syrian hamsters were kept individually (controls) or with 3, 5, 7 animals per cage. The crowded animals showed a significant decrease in mean survival time. This was linked to a histopathological examined significant increase in the extent and incidence of amyloidosis in several organs of both male and female hamsters. The kidneys and adrenals were most affected. Chronic inflammation as one probable amyloidosis-inducing factor, was not related to the observed morphological alterations. Furthermore the increase of amyloidosis was statistically not connected with an age-dependent development of amyloidosis. Amyloidosis in Syrian hamsters may be not a mere phenomenon of aging and age-related decline of the immune system but rather the results of a complex set of variables, including factors of social environment and social interactions that continuously put stress on the hamsters.