There is higher genetic similarity between friends than expected by chance (Christakisa & Fowler, 2014). The cues friends use in order to identify genetically similar individuals remain unknown. Since human body odor is linked to genetic makeup (Jacob et al., 2002), we hypothesized that people tend to befriend others who smell similar to them. To test this, we identified 20 dyads who reported “clicking” when they first met, and collected their body odor. In Experiment 1 we examined whether pairs of body odors collected from such click dyads smelled more similar than those of random dyads, using an electronic nose (eNose) – an analytical device made of sensors providing a representation of odor. Remarkably, we found that click dyads indeed have a more similar smell. In Experiment 2 to test whether humans could do what the eNose did, 25 participants rated the odor similarity of dyads using visual-analogue scales (VAS). Click dyads were rated as significantly more similar than random dyads. These results indicate that “click friends“ may smell like each other, but could similar body odor serve as a predictor for a future friendship? To address this question, in Experiment 3 we collected body odor from 17 strangers and using the eNose we measured the body odor similarity between each possible within-sex dyad. Next, 66 dyads comprised of the 17 strangers played the “Mirror Game”, in which they had to move their hands in sync, when standing next to each other to ensure smelling of their partner’s body odor, and later indicate their feelings towards the other participant. We found that body odor similarity predicted positive social interaction and clicking. These converging results shed light on subliminal mechanisms underlying friendship formation, a critical aspect of human social interaction.