To date, a variety of mobile devices have emerged as healthcare tools. In particular, when they are integrated with advanced optical imaging techniques such as multispectral imaging and analysis, it would be very useful for early diagnosis of malignant and non-malignant skin diseases as well as quantitative monitoring of prognosis of the diseases after their treatment at home. Thus, we here demonstrate smartphone-based multispectral imaging and analysis for mobile diagnosis of various skin diseases. We first underlie how to develop smartphone-based multispectral imaging systems. We also investigate their potentials for mobile diagnosis of various skin diseases including acne, seborrheic dermatitis, psoriasis, and etc. In particular, we highlight that the smartphone-based multispectral imaging and analysis allows us to quantitatively monitor acne regions during their treatments with benzoyl peroxide and also to discriminate between seborrheic dermatitis and psoriasis occurred on the scalp with high sensitivity and specificity at ubiquitous environments. Furthermore, we discuss its potentials for mobile healthcare such as recommendation of personalized cosmetics.