The relationship between vitamin D and skin diseases is undeniable. For this reason, knowing the characteristics, physiology and effects on the body is key in the medical confrontation. Currently it is known that vitamin D corresponds to an immunomodulatory molecule with multiple pleiotropic effects in the human body. The vitamin D receptor is expressed in various cells of the body highlighting the cells of the immune system, brain, heart, skin, musculoskeletal, gonads, prostate, breast, and digestive system. Current evidence shows that changes in vitamin D levels have a great impact on patients with psoriasis, atopic dermatitis, vitiligo, systemic lupus erythematosus, systemic sclerosis, cancer, among other conditions. Therefore, this article aims to inform about the fundamental aspects of vitamin D and its relationship with the main skin diseases.