We have observed six highly metal-deficient dwarfs in the spectral range containing the resonance doublet of 9Be II at 3130 Å. Using the method of spectral synthesis we have evaluated the abundance of 9Be in these objects. In three of the stars, those with metallicities [Fe/H] < -1.5 we set upper limits to the 9Be abundance, 9Be/H, below 2.5 10-12, and in the other three, those with -1 > [Fe/H] > -1.3 we reported detections of 9Be with abundances in the range 1 10-12 < 9Be/H < 2.5 10-12. These are the first reported detections of 9Be in stars with such low metallicities. From our results and literature values for 9Be in more metallic stars, we can constrain models for galactic evolution: those which entail an early burst of 9Be production are ruled out. The data are used to predict the spallogenic content of 7Li, 6Li, 10B and 11B in the material from which the sample stars was formed and hence to limit the galactogenic fraction of 7Li in highly metal-deficient stars. A firm upper limit of 0.1 dex can be set to the fraction of measured 7Li in such stars which is either non-primordial, or is due to spectral blending of 6Li, leaving virtually all of the measured 7Li as primordial.