The objective of this study was to evaluate leaf cuticular wax constituents of soybean (cv A4100) and their response to water deficit. Water deficit was imposed by withholding irrigation until leaf water potential drop to -2,7 MPa, at this point the plants were irrigated to field capacity and then a new cycle started. Several drought cycles were applied from R2 to R5. Plants were kept under field capacity the rest of the time. All water deficient plants showed a significant increase in wax amount (approximately 3 times per unit area), compared to irrigated plants. Leaf cuticular waxes were dominated by alkanes (73%), wax esters (12%), methyl esters (6%), free fatty acids (6%) and triglycerides (4%). The major alkane constituents were odd-chain components, the most abundant being the C27, C29, and C31 homologues, whereas the major wax esters were even-chain saturated fatty acids (C16-C20 predominantely) plus some 18:1 and 20:1 esterified to very-long-chain alcohols. The distribution of hydrophobic chains within the methyl esters showed this fraction to be peculiarly rich in C24, C26, and C28 components (more than 80%) whereas the proportion of free fatty acids with more than 20 C increased significantly (54 to 72%) under water deficiency. In the triglycerides, 75% of the fatty acids had 16 and 18 C, including unsaturated fatty acids such as 16:1 and 18:1, 18:2 and 18:3. The five components analyzed, accounted for 40% of the total amount of surface lipid present in irrigated plants (151 ± 10 µg dm^-2) but to 60% (617 ± 37 µg dm^-2) in plants under water deficiency. After a suitable period of rehydration, previously stressed soybean leaves, produced more wax than leaves prior to stress and chemical alteration may represent a physiological-adaptive response of soybean plants to water deficiency.