Several markers have been developed for the biochemical monitoring of Gaucher disease. Three of the most commonly used markers are acid phosphatase, angiotensin-converting enzyme (ACE) and chitotriosidase. The rationale for using all three concurrently is not clear. A retrospective study was therefore carried out on data collected from 28 paediatric patients treated with enzyme replacement therapy. All three markers fell with time. However, chitotriosidase showed the steepest time trend, the largest trend by case interaction, and the lowest residual variance, making it the most reliable of the three. ACE correlated strongly with chitotriosidase, but acid phosphatase did not correlate well with either and also had the largest residual variance, indicating that it was too 'noisy' to be informative. The absence of a 'gold standard' for assessing Gaucher disease complicates the interpretation of these findings, but they suggest that acid phosphatase be dropped from routine clinical practice, and that chitriosidase be used in preference to ACE.