This study examined the effects of product recommendation services as an atmosphere for online mass customization shopping sites on consumers` cognitive and affective responses. We conducted a between-subject experimental study using a convenience sample of college students. A total of 196 participants pro-vided usable responses for structural equation modeling analysis. The findings of the study support the S-O-R model for a product recommendation system as an element of the shopping environment with an influ-ence on OMC product evaluations and arousal. The results showed that OMC product recommendation ser-vice positively affected cognitive and affective responses. The findings of the study suggest that OMC re-tailers might pay attention to the affective and cognitive responses of consumers through product recommend-dation services that can enhance product evaluations and OMC usage intentions.