Gaucher disease is caused by the inherited deficiency of glucocerebrosidase, a lysosomal enzyme responsible for the cleavage of glucosylceramide. In addition to organomegaly and hematological abnormalities, type 1 (nonneuronopathic) disease is characterized by insidiously progressive and often severe skeletal involvement. We investigated the applications of biochemical markers of bone turnover in the evaluation of skeletal lesions in type 1 Gaucher disease patients. Serum osteocalcin, a marker of osteoblastic bone formation, and type I collagen C-terminal telopeptide, a marker of osteoclastic bone resorption, were measured in 16 type 1 Gaucher disease patients and in 29 age-matched controls. Our results indicate a significant decrease of both osteocalcin (11.13 +/- 2.27 ng/ml) and type I collagen C-terminal telopeptide (3617.62 +/- 536.69 ng/ml) values in patients with Gaucher disease, compared to the unaffected controls (38.67+/-6.24 ng/ml and 6808.57 ng/ml +/- 865.66, respectively). These low values were observed in all patients, irrespective of their age, indicating a marked failure of both osteoblastic and osteoclastic functions in Gaucher disease. Significant differences in the mean serum values of biochemical bone turnover markers were found in different evolutional stages of bone involvement. We conclude that measurement of serum biochemical markers of bone turnover can be used as an auxiliary tool in the diagnosis, staging, and monitoring the skeletal lesions in Gaucher disease, in conjunction with imaging methods and bone densitometry measurements.