The case study of a 12 - year-old girl with allergic disposition is discussed. During an acute feverish condition accompanied with a number of complications, the IgM lambda paraprotein was found in the serum sample. In the subsequent control electrophoresis which was carried four months later, this paraprotein was not found any more. Literature dealing with the problems of transient paraproteinemias is included in this work and possible causal relations are discussed. Transient paraproteinemias seem to be more frequent than originally assumed.

        Key words: transient paraproteinemia, infections.