Through 1975 published measurements of 228Ra in most geochemical samples have been calculated using a 6.7 year half-life for 228Ra. The currently accepted half-life is 5.75 years and was established in 1962. Measurements as early as 1908 indicated a value of about 5.5 years, but a 1918 measurement giving a 6.7 year half-life was adopted and remained unchallenged until 1960. Seawater 228Ra activities calculated using a 6.7 year half-life are probably no more than 4% low, and approximately 2% low on the average. Therefore, data that have appeared in the literature are not significantly altered by the new value. Diffusion coefficients derived from the distribution of 228Ra in seawater are generally 8% to 20% low due to possible errors in the calculated activities and use of the wrong decay constant. Coral growth rates derived from the distribution of 228Ra in modern corals are about 14% low.