Résumé : A study has been made of the decay sequence 12ΛB → π- + 12C* → π- + 4He + 4He + 4He. From a comparison of the measured branching ratios to certain states of 12C and the angular correlations observed in their decays with those predicted by Ziemińska and Dalitz, it is concluded that the spin of the hypernucleus 12ΛB strongly favours the value of unity. © 1974.