Despite intensive research of biochemical processes, underlying aging and, hence, nutritional disorder, currently there is no available routine laboratory method allowing objective diagnosis or control of malnutrition. Diagnostic strategy in different types of malnutrition (prelatent, compensated and decompensated) and the value of potential laboratory markers of malnutrition (proteins, vitamins, trace elements etc.) are considered. The author concludes, that diagnosis of malnutrition currently represents a serious problem, especially for "geriatric" laboratory diagnostics.