Gymnosperms show a significantly higher mean (1C=18.16, 1Cx=16.80) and a narrow range (16.89-fold) of genome sizes as compared with angiosperms. Among the 12 families the largest ranges of 1C values is shown by Ephedraceae (4.73-fold) and Cupressaceae (4.45-fold) which are partly due to polyploidy as 1Cx values vary 2.41 and 1.37-fold respectively. In rest of the families which have only diploid taxa the range of 1C values is from 1.18-fold (Cycadaeae) to 4.36-fold (Podocarpaceae). The question is how gymnosperms acquired such big genome sizes despite the rarity of recent instances of polyploidy. A general survey of different families and genera shows that gymnosperms have experienced both increase and decrease in their genome size during evolution. Various genomic components which have accounted for these large genomes have been discussed. The major contributors are the transposable elements particularly LTR-retrotransposons comprising of