Compliance with the prescribed medical regimen is a critical factor for the continued well-being of hemodialysis patients. As compliance is a multifactorial problem, numerous approaches have been utilized to quantify the compliance of hemodialysis patients. In the present study, we have attempted to examine whether unanticipated control of biochemical indices might predict the compliance status of hemodialysis patients. We compared unanticipated mid-month values of blood urea nitrogen (BUN), serum potassium (K) and phosphate (PO 4 ) values of 54 maintenance hemodialysis patients with the scheduled, regular first-week measurements during a 6-month study period. The interdialytic weight gain (IWG) levels of the corresponding weeks were also compared. Mid-month analysis revealed a significant deviation in the compliance status of the study population as BUN, serum K and IWGs were concerned (p 4 levels were also higher but the difference was not significant (p < 0.05). In conclusion, the differences observed in biochemical indices upon change of test request timing were distinctive. It suggests that unanticipated control of biochemical indices might contribute to the actual assessment of compliance in hemodialysis patients.