Repeated clusters of blisters on a moist penis may be caused by genital herpes, genital eczema, and acute superficial glans. 1. Genital herpes: repeated clusters of blisters on a moist penis may be caused by genital herpes, which is a sexually transmitted disease caused by the herpes simplex virus. The manifestation of small blisters around the anus or external genitalia, patients will also be accompanied by pain, fever, fatigue and other systemic symptoms. 2. Genital eczema: penis moisture repeatedly long clusters of blisters may be caused by genital eczema, manifested as intense itching of the skin, diffuse redness, swelling, after scratching and friction blisters rupture, can form a large vesicles, scabs. 3. Acute superficial glans: Penile dampness repeated long clusters of blisters, may also be caused by acute superficial glans. Performance for the glans or penis pain, burning and itching sensation, and clothing friction aggravated. In severe cases, blisters or ulcerated surfaces may appear, and there is a milky-white foul-smelling purulent discharge, accompanied by urethral urethral erythema. Patients with symptoms of penile moisture repeated long clusters of blisters, it is recommended to go to the hospital in a timely manner to avoid delaying the condition and causing adverse consequences.