The purpose of the study was to establish the reference ranges of serum creatinine and estimated creatinine clearance for adult Kenyan population using enzymatic sarcosine oxidase quantitative analytical method. A prospective study carried out in clinical chemistry laboratory of Kenyatta National Hospital involving 631 individuals between 18-61 years. Results for 316 study subjects (158 renal patients and 158 healthy subjects) were used to compare the difference between enzymatic sarcosine oxidase and modified jaffes reaction methods. Comparison of the two methods showed statistically significant difference (renal patient: p = 0.024, healthy subjects: p = 0.038). Parametric methods were used to construct reference ranges by estimating 2.5 and 97.5 percentiles of distribution as lower and upper reference limits. Results for 462 blood donor study subjects comprising of 249 male and 213 females were used for the establishment of reference ranges of:- serum creatinine and estimated creatinine clearance. Serum creatinine and estimated creatinine clearance reference ranges established were as follows:- serum creatinine {male: (41-109) μmol/L, female: (32-92) μmol/L} and estimated creatinine clearance {male: (36-98) ml/min, female: (31-81) ml/min}. The current study has established adult Kenyan reference ranges for serum creatinine and estimated creatinine clearance using enzymatic sarcosine oxidase analytical method. Enzymatic sarcosine oxidase method produced low creatinine concentration than the modified jaffes reaction method for the studied parameters.