Abnormalities of the nails can provide both subtle and obvious clues t
o common medical problems or severe systemic diseases. Heredity, minor
injuries and a variety of infections account for many changes in the
appearance of nails. Several dermatologic disorders, such as psoriasis
and alopecia areata, and other multisystem disorders may present with
nail changes; abnormalities of the nails may be the single most promi
nent feature. Common habits and the use of various cosmetics also may
result in nail changes. Awareness of normal nail variants and well-def
ined abnormalities and their disease associations will be beneficial t
o most clinicians. Specific management and therapy for most nail probl
ems are usually simple and appropriate for primary care physicians.