Skin-surface lipids from the monkey Macaca fascicularis are composed of sterol esters (38%), cholesterol (4%) and two types of wax diesters, identified as Type II (IIa and IIb, 17% and 40%, respectively). Type IIa contained diesters of 1,2-alkanediols esterified with two molecules of long-chain (C14-C34) fatty acids having straight and branched chains. In the diesters IIa, fatty acids shorter than C19 predominated in position 1, and fatty acids longer than C20 predominated in position 2. Type IIb contained diesters of 1,2-alkanediols esterified with C4 and C5 branched-chain fatty acids (predominantly isovaleric acid) at position 1 and long-chain (C14-C27) acids, having straight and branched chains, at position 2. The short-chain acids were converted to 2-nitrophenylhydrazides and analyzed by high-performance liquid chromatography (HPLC). Ammonia chemical ionization (CI)-gas chromatography (GC)-mass spectrometry (MS) resolved the intact diesters IIb into 12 peaks corresponding to molecular weights ranging from 597 to 748, and showed that the molecular species, such as C21-C16-C5 (diol, fatty acid in position 2, fatty acid in position 1), C22-C16-C5 and C23-C16-C5, were prevalent. The fatty acids from both diesters were mostly (greater than 98%) saturated. The 1,2-alkane-diols from both diesters consisted of C16-C26 saturated straight- and branched-chain components. The acyl groups of sterol esters contained 86% C14-C34 branched-chain acids.(ABSTRACT TRUNCATED AT 250 WORDS)