Seasonal dynamics of major biochemical features were studied for three abundant egg-diapausing copepods Acartia bifilosa, Centropages hamatus and Temora longicornis, in the White Sea (66°N), between June 2002 and September 2002. Dry weight (DW) and prosome length varied from 0.54 μg ind -1 and 0.163 ± 0.012 mm (A. bifilosa, CI) to 9.58 ± 0.72 μg ind-1 and 1.135 ± 0.167 mm (C. hamatus, females). Corg and Norg content reached up to 5.91 ± 0.44 and 1.23 ± 0.09 μg ind-1 (C. hamatus, females). Protein and lipid content varied greatly from 31.8 to 67.3% DW and from 8.7 to 42.6% DW, respectively. These species show somewhat different biology compared to species at lower latitudes. The copepods use lipid stores to survive during short-term food shortage (e.g. in autumn) and successfully complete their life cycle. In the isolated White Sea during last post-glacial period, species probably evolved some special biochemical features (especially wax esters presence). Food quality demands and long ice coverage are possible factors limiting early development of species in spring. © 2008 The Author(s).