Eastern Antarctic sea ice algal biomass were measured in the spring of 2002, 2003 and 2004. Productivity was measured by 14C in 2002 and by oxygen electrodes in 2002 and 2004. Biomass was low, in the range 0.01 to 8.41 mg Chl a m-2, with an average of only 2.08 � 1.74 mg Chl a m-2 (n=199). Most locations had an increased concentration of algae at the bottom of the ice. This development of bottom ... communities was most pronounced in ice between 0.5 and 1.0 m thick. There was also evidence that locations between latitudes 64�S and 65�S had greater sea ice algal biomass than locations either north or south of this zone. Productivity was determined both by in situ oxygen electrode techniques and on board C14 incubations. Maximum in situ production (2004) was approximately 2.6 mg C m-2 h-1 with assimilation numbers of 0.73 mg C (mg Chl a)-1 h-1. Maximum assimilation numbers determined by the C14 incubations (2002) varied between 0.031 and 0.457 mg C (mg Chl a)-1 h-1. Maximum fluorescence quantum yields of the incubated ice samples (2002) were 0.470 � 0.041 with Ek indices between 19 and 44 mol photons m-2 s-1.and consistent with the shade adapted character of ice algal communities.