SUMMARY.1. The biomass distribution of submerged vascular vegetation and benthic fauna were investigated by diving in Lake Kariba. The vegetation was well correlated with transparency of the water. Maximum biomass (1400 g dryweight m−2) and a depth penetration of 6 m were found in areas little influenced by river inflow, while these were only 110 g m−2and 2 m, respectively, in the basin receiving water from the Zambezi river.2. The lake is mesotrophic‐oligotrophic. The total biomass for the lake was 101,000 tons dryweight of rooted vegetation composed ofLagarosiphon ilicifoliusOberm. (52%),Najas pectinata(Parl) Magnus (33%),Vatlisneria aethiopicaFrenzl (11%),Ceratophyllum demersumL. (3%) andPotamogeton octandrusL. (0.5%). Average plant biomass for the potentially colonizable depth zone of 0‐12 m and for the total lake amounted to 79.9 g m−2and 18.8 g m−2, respectively.3. The distribution of the benthic fauna generally followed that of the vegetation. The total animal biomass of 118,840 tons dryweight. including shells, consisted of mussels (95.8%), snails (4.1%) and insect larvae (0.1%). Four species of mussels were found:Caelatura mossambicensis(von Martens) (81% of mussel biomass),Corbicula africana(Krauss) (9%).Mutela dubia(Gmelin) (5%) andAspatharia wahlbergii(Krauss) (5%). Among the snailsMelnoides tuberculuta(Müller),Cleopatraspp. andBellamya capillata(Frauenfeld) dominated.4. The average animal biomass was high compared to most other lakes perhaps due to lack of predators. For the colonizable 0‐12 m depth interval and the total lake it was 96.2 g m−2including shells (15.0 g m−2shell‐free dryweight) and 22.6 g m−2including shells (3.4 gm−2shell‐free dryweight). respectively. Biomass of plants and animals was even higher prior to the recent lowering of the water level by 7 m, which was estimated to have stranded 84,000 to