Recently, comorbidities have been rediscovered in dermatology. Although numerous associations between skin diseases and other conditions have been reported, only a few are well documented. The association of comorbidities and dermatoses is complex and multifactorial. Life-style factors, impaired health-related quality of life, depression, therapeutic interventions, and several biases may confound the relationship between skin diseases and comorbidities. This article discusses observational studies that assess comorbidities in psoriasis, atopic dermatitis, vitiligo, and nonmelanoma skin cancer, and the likelihood of the observed associations and their clinical consequences.