The results of the present study demonstrate that spider monkeys possess a well-developed olfactory sensitivity for aliphatic ketones. The length of the carbon chain was found to be an important molecular feature as the olfactory sensitivity increased with the length of the carbon chain. Positioning of the functional group, however, did not affect the spider monkeys’ olfactory sensitivity. Also, the across-species comparison of the threshold values for aliphatic ketones in Spider monkeys, Squirrel monkeys, Pigtail macaques and humans did not indicate systematic differences in olfactory sensitivity between the species. Thus, no correlation between olfactory sensitivity and relative size of anatomical brain structures or the number of functional olfactory receptor genes was found. This suggests these anatomical and genetic features to be of less importance for olfaction in primates.