This paper discusses biomonitoring using mosses as a technique used in programs for investigating trace-element air pollution. Emphasis is given to mosses as the dominant plant species used in biomonitoring surveys. Biomonitoring is regarded as a means to assess trace-element concentrations in aerosols. Current literature is reviewed for moss biomonitors and their physiological process responsible for accumulation of element concentration. Attention is given to the principles, selection of the moss species as biomonitors for air pollution and the possibilities for employing biomonitoring techniques in future studies. Combining the integrating property of moss biomonitors with availability and uniform matrix characteristics of air particulates as a prerequisite for monitoring of air pollution is discussed.