The role of Demodex mites in the pathogenesis of skin diseases still needs updating. The aim of the study was to determine the relationship between Demodex sp. infestation and ocular and skin lesions in patients with atopic dermatitis (AD) and psoriasis (PsO). The control group comprised subjects that had not been diagnosed with any inflammatory skin disease. Direct microscopic examination (DME) was applied to analyze eyelashes and skin scraping samples. Demodex mites were detected more often in the eyelash samples than in the skin in both the AD (16.7% vs. 6.7%) and PsO (18.5% vs. 7.4%) patients as well as in the control group (25.8% vs. 3%). The mean intensity of Demodex infestation was 4.25 in the AD patients, 3.4 in the PsO patients, and 2.8 in the control group. Emollients were used in the treatment by 76.7% of the AD patients and 64.8% of patients with PsO; however, this type of skin care did not significantly increase the risk of skin colonization by Demodex. AD and PsO do not seem to facilitate excessive Demodex sp. proliferation. Nevertheless, diagnosis of the presence of these mites should be considered in patients with facial skin and ocular lesions that do not respond to the treatment.