Comparative studies on the effect of temperature treatment on the endogenous polyamine content in wild type and the ethylene insensitive mutant eti5 of Arabidopsis thaliana (L.) Heynh were performed. The levels of free and conjugated putrescine, spermidine and spermine were measured in rosette leaves of 38-day-old plants subjected to low and high temperature for 24 h in darkness. Data for fractions measured in treated wild type plants during recovery suggest that alterations in polyamine levels may be a consequence of the conversion of the supernatant-bound into free form and vice versa, while in treated eti5 plants de novo synthesis of spermidine and spermine could not be excluded. It was found that high temperature provoked more significant changes in polyamine levels than low temperature. The results suggest that the eti5 mutant showed a better ability to recover after the temperature treatments than wild type partly as a consequence of changes in polyamine content.