Chronic kidney disease (CKD) is a major public health problem worldwide. Until now, no large-scale data about the prevalence of pre-dialysis CKD has been reported in Thailand.The clinical and laboratory data from the ground air force personnel who were routinely checked up during 2002-2003 were collected and descriptively analyzed. The pilots and air crews were excluded. All personnel were working in Bangkok.15,612 RTAF personnel completed the annual check up. Eighty-two percent were male. The average age was 45.7 +/- 8 (19-65) years. According to the classification of stages of CKD by Kidney Disease Outcome Quality Initiative (K/DOQI), the prevalence of CKD is 9.1% by Cockcroft Gault formula and 4.6% by Modification of Diet in Renal Disease. Patients with diabetes mellitus, hypertension, hypercholesterolemia and proteinuria were found in 8.2%, 45.8 %, 28.2 % and 1.8% respectively. CKD patients were older had higher body weight, Body Mass Index (BMI), blood pressure and blood sugar than non CKD personnel.CKD were not uncommon among RTAF personnel. The Cockcroft-Gault and MDRD equations were different in detecting CKD in the present study. The appropriate equation to determine GFR in Thai population should be evaluated. Low sensitivity of dipstick proteinuria may cause the low prevalence of stage 1 and 2 CKD.