The Subukia Valley earthquake in East Africa, magnitude 6.9, occurred on 1928 January 6. This is a little known earthquake associated with a 38 km long surface break that showed normal faulting with a small component of left lateral motion. Maximum throw was 240 cm with an average along the rupture of less than 100 cm. The earthquake triggered rockfalls and minor landslides and exhibited long-period effects at large distances. Considering the magnitude of the earthquake, the amount of damage it caused was not as great as it could have been. This is directly attributable to the sparsity of dwellings and the inherent resistance to earthquake shaking of the local type of huts. In the process of studying this earthquake, the seismicity of the (Gregory) Kenya Rift Valley has been re-evaluated. It is shown that relatively large but infrequent earthquakes do occur in the Kenya (Gregory) Rift Valley, a slowly extending region of low apparent seismicity, and that the seismic hazard of this part of East Africa, deduced from data of the last 95 years, is significant.