Affinity 2.5 is a computer-based instrument designed to measure sexual interest using viewing time of images depicting fully-clothed males and females of different ages. Participants are asked to rate the sexual attractiveness of the person in the image according to a 15-point scale while their viewing time of each image is surreptitiously monitored. The validity of viewing time as a measure of sexual interest is based on social cognition theory and is established in the review of literature. The number of images comprising Affinity 2.5 represents a 42.9% increase from the previous version of the assessment, Affinity 2.0. The purpose of this study was to examine the temporal stability of scores on Affinity 2.5 for a sample of exclusively heterosexual, nonpedophilic males and females. Viewing time data from 63 males and 84 females were analyzed using a chi-square procedure. Results of this analysis indicate that 86% of responses from the male participants and 88% of responses from the female participants were consistent from time one to time two. As suspected, these percentages represent an increase in reliability over the temporal stability of the shorter Affinity 2.0.