Abstract The beryllium concentration of 17 meteorites has been determined with excellent precision by a fluorometric procedure using morin as reagent. The average concentration found for 13 chondrites and 1 achondrite was 0·038 p.p.m or 0·64 atom per 10 6 atoms of silicon. Two other achondrites were excluded from the average because of their large deviations from the mean. The only iron meteorite analysed contained less than 1 p.p.b. as expected. One sample each of a diabase, basalt, granite and shale showed an increasing quantity of beryllium in the order given compared to the meteorite average, ranging from about 16 times for the diabase to 160 times for the shale. Values of 2·74 ±0·03 p.p.m. and 0·623 ±0·006 p.p.m. were obtained for the standard rock samples G-l and W-l, respectively.