Neuroimaging studies have found a correlation between activation in the anterior insula and love, and a correlation between activation in the posterior insula and lust. The present control-case study describes a neurological male patient, with a rare, circumscribed lesion in the anterior insula, whom we tested using a decision task that required he judge whether each of a series of attractive individuals could be the object of his love or lust.  The patient, in contrast with neurologically typical participants matched on age, gender, and ethnicity, performed normally when making decisions about lust but showed a selective deficit when making decisions about love. These results provide the first clinical evidence indicating that the anterior insula may play an instrumental role in love but not lust more generally. These data support the notion of a posterior-to-anterior insular gradient, from sensorimotor to abstract representations, in the evaluation of anticipatory rewards in interpersonal relationships.