An enzyme which splits reduced NAD has been partially purified from pea ( Pisum sativum, Kelvedon Wonder) seeds. The activity requires orthophosphate and the products are ADP and probably NMN (dihydro NMN?). The enzyme splits the NADH 2 at the pyrophosphate bond and incorporates the phosphate into the AMP residue. NAD, NADP or NADPH 2 could not replace NADH 2. The enzyme is unstable during storage, is activated by Mg 2+ and by Mn 2+, and inhibited by Ca 2+. K +, Li + and NH 4 + have no effect. The possible role of this enzyme in the synthesis of ATP in seeds at the early stage of germination is discussed.