Ξ0 beta decays at KTeV

The new KTeV beam line and detector at the Fermilab Tevatron have been operating in 1996 and 1997. The experiment 799 at Fermilab was the rare decay run of the KTeV apparatus. Besides collecting a large number of neutral kaon decays, the apparatus was used to trigger for rare decays of neutral hyperons. We present the status of our measurements of the hyperon beta decays Ξ0 → Σ+ e- v-bare, as well as evidence for the first observation of /-bar0 → /-bar- e+ ve and Ξ0 → Σ+ μ- v-barμ