Benign transient hyperphosphatasia (BTH) is a condition that occurs mainly in infants and children and is characterised by a transient increase of serum alkaline phosphatase (ALP) activity up to several fold the adult upper reference limit (URL). The present report concerns BTH in 2 patients, aged 59 and 52 years old, who showed no evidence of bone or liver disease but had an increase in ALP activity up to 20-fold and 13-fold the adult URL, respectively. The diagnosis of BTH in the first case was made retrospectively, and after excluding liver and bone disease. However, in the second case the diagnosis was made early in the course of the disease, by performing an ALP isoenzyme electrophoresis test. Lengthy and extensive investigations were avoided in the second case. These cases highlight the occurrence of this condition in adulthood as well as in infancy and childhood.