Using steel pins inserted into growing moss colonies near Casey Station, Wilkes Land, continental Antarctica, we have measured the growth rate of three moss species: Bryum pseudotriquetrum and Schistidium antarctici over 20 years and Ceratodon purpureus over 10 years. This has provided the first long-term growth measurements for plants in Antarctica, confirming that moss shoots grow extremely slowly in Antarctica, elongating between 1 and 5 mm per year. Moss growth rates are dependent on availability of water. Antheridia were observed on some stems of B. pseudotriquetrum; no archegonia or sporophytes were observed. Stems bearing antheridia elongated much more slowly than vegetative stems in the same habitat. Two other methods of growth rate measurement were tested, and gave similar rates of elongation over shorter periods of time. However, for long-term measurements, the steel pin measurements proved remarkably reproducible and reliable.