The fall-out of 239Pu and 238Pu has been investigated by studying samples of various species of lichen collected during 1947–1961 at different places in Scandinavia and between 1961 and 1972 (Cladonia alpestris) at Lake Rogen in Sweden, which lies at 62.3°N, 12.4°E. The maximal 239Pu level in the lichen carpet, which occurred in 1963, was about 300 pCi per kg dry weight, and it decreased to about 200 pCi per kg dry weight in 1970. The mean residence time for 239Pu in the whole lichen carpet was estimated to 6.1 ± 0.5 yr and in the 3-cm top layer to 4.3 ± 0.5 yr. The 238Pu concentration showed a maximum value during 1963 corresponding to about 12 pCi per kg dry weight. This concentration decreased to about 7 pCi per kg dry weight in 1967. During 1966–1970 the 238Pu concentration increased and resulted in an increase of the 238Pu/239Pu activity ratio from 0.026 ± 0.003 to 0.046 ± 0.003. The total area-deposition of 239Pu at the sampling place (62.3°N, 12.4°E) was estimated to 1.0 ± 0.1 mCi*km−2 in 1972. The corresponding value for 238Pu was 0.036 ± 0.004 mCi*km−2 of which 0.013 ± 0.002 mCi*km−2 was due to SNAP-9A. The vertical distribution of the plutonium isotopes in the lichen carpet has also been studied. Results of the 239Pu-activity concentrations in reindeer liver and bone indicate a fractional gastrointestinal absorption of plutonium in reindeer in the order of (3 ± 2) * 10−5.