OBJEIVE A simple nomogram was construed to estimate the absorption rate coefficient (Ka) using the peak time (tpeak) and the elimination rate coefficient (ke) of drugs administered orally. METHOD The nomogram was based on the plasma concentration-time curve and the funion relation between tpeak,ka and ke. A mathematical analysis was presented which allowed for the construion of single chart nomogram. To check on the degree of accuracy of the developed nomogram. It was used to analyze retrospeive profiles of 46 drugs and compared the ka alues from nomogram and those calculated by solving the equation. To analyze the performance error, the measured carbocisteine concentrations were compared with the predied concentrations by ka from the nomograms along with the other pharmacokinetic parameters. RESULTS The estimations of ka values from nomogram were in very close proximity with the numerical values. The performance error was as follow MDPE and MDAPE are 1.3% and 18.2%, respeively. CONCLUSION The developed nomogram is accurate and reliable. The sive of performance error meets the demand of clinical pharmacokinetics. The nomograms may offer another convenient and easy method for rational individualized dosage regimen.