Recent studies of Lake Ladoga ringed seal have included estimation of population size, studies on morphology and behaviour of this subspecies, and analyses of some environmental toxicants in the tissues of recovered carcasses. Compared with the Baltic ringed seal, and especially with the Saimaa seal, the population status of the Ladoga ringed seal is good. The population probably includes over 5000 animals. The body of the Ladoga seal is smaller than that of the Saimaa seal or the Baltic ringed seal; its pelage is darker and also craniometrically the Ladoga seal clearly differs from the other subspecies of ringed seal. During summer in Northern Ladoga, the Ladoga ringed seal forms haul-out herds of more than 50 animals. During haul-out in herds the Ladoga seal actively uses different vocalizations. Concentrations of mercury in the liver and kidney of the Ladoga seal are clearly elevated, but levels of the other environmental toxicants analyzed (Cd, Pb, PCB) are comparatively low.