Among different species of mites, Demodex folliculorum and Demodex brevis are the only 2 that affect the human eye. Because demodicosis is highly age-dependent and can be found in asymptomatic adults, the pathogenicity of these mites has long been debated. In this study, we summarize our research experience including our most recent study regarding Demodex infestation as a potential cause of ocular inflammatory diseases. Specifically, we describe the pathogenesis of demodicosis and then discuss the results of work investigating the associations and relationships between ocular demodicosis and blepharitis, meibomian gland diseases, and keratitis, in turn. This is followed by some discussion of the diagnosis of demodicosis and concludes with a brief discussion of evidence for different treatments for ocular demodicosis. Collectively, our studies suggest a strong correlation between ocular demodicosis and ocular surface inflammatory conditions, such as blepharitis, chalazia, meibomian gland dysfunction, and keratitis. Further investigation of the underlying pathogenic mechanism is warranted.