Hydrocarbons occurring in the external lipids and in the internal lipids of fresh spinach leaves were separately isolated by TLC and then were identified by gas-liquid chromatography in conjunction with Molecular Sieve 5A treatment and catalytic reduction. The external lipids contained 10% hydrocarbons which were normal paraffins: n-C27 to n-C33 showing a clear odd-number preference, and n-C31 predominating. On the other hand, the internal lipids contained only 0·1% hydrocarbons, principally hydrocarbons similar to those found in the external lipids, n-C31 predominating, but, in addition, a significant proportion of a new series of aliphatic paraffins, n-C16 to n-C28 not showing odd-number preference, was present. The presence of these two distinctive carbon ranges of aliphatic paraffins in spinach suggests that there are two different enzyme systems responsible for their synthesis. © 1970.