Although subclinical enthesopathy is a well-established diagnostic criterion for psoriatic arthritis (PsA), it is frequently overlooked, as many patients are asymptomatic. The possibility of finding a clinical clue predicting enthesopathy would help clinicians establish an early diagnosis of PsA. A prospective single-center study of a total of 90 patients with psoriasis was conducted to assess the presence of entheseal abnormalities as detected by ultrasound, and to determine any correlation with nail involvement. Entheseal abnormalities were found in 23 patients (25.5%), 19 (82.6%) of whom showed nail involvement, whereas four (17.4%) individuals did not. Enthesopathy was present in 31.1% (19/61) of patients with onychopathy compared to 13.8% (4/29) of those without nail involvement (p = 0.07). There was a significant correlation between target NAPSI score and evidence of enthesopathy. In addition, the number of nails affected also showed a significant correlation with the presence of enthesopathy (p = 0.035). Clinical evidence of onychopathy may be the clue to an early diagnosis of enthesopathy in psoriasis patients.