Background: With the COVID-19 infection speeding around the world, many experience fear and anxiety. To detect those at risk of psychopathology and provide treatment, valid instruments are needed. The aim of this study was to cross-culturally validate the theory-based instrument Multidimensional Assessment of COVID-19-Related Fears (MAC-RF) in Croatian and to further examine the scale’s validity by exploring its relationship with relevant constructs. Method: A total of 477 participants completed an online survey during a rapid rise in new daily COVID-19 cases in Croatia and while new restrictions were being imposed. Results: MAC-RF had a stronger association with health anxiety, cyberchondria, and anxiety sensitivity compared to depression, attesting to its convergent and divergent validity. However, a 2-factor structure was revealed in this sample: Fear of infection and Fear of using an inadequate strategy in dealing with pandemic. Fear of infection had a stronger association with health anxiety and COVID-19 anxiety and was a better predictor of COVID-19 related protective health behaviors. Fear of choosing an inadequate strategy had a stronger association with cyberchondria, fear of consequences of the epidemic on mental health, as well as financial consequences, and loss of civil liberties. Conclusion: Fear of infection captures negative emotional states due to feared consequences on personal somatic health and the health of loved ones, while Fear of choosing an inadequate strategy in dealing with the pandemic reflects a metacognitive aspect. Treatments may have to target both aspects of COVID-19 related fear.