The chronopharmacokinetics of paracetamol was studied in six male volunteers. Serum concentrations of paracetamol were determined after a single oral dose of 1 g, on three occasions, spaced at least 1 week apart. Plasma drug concentration vs time curves were obtained after dosage at 08.00 h (Day 1), 14.00 h (Day 2) and 20.00 h (Day 3), under standardized conditions. Pharmacokinetic parameters compared were t1/2,alpha, t1/2,Z, tmax, Cmax and AUCpo. No statistically significant differences were found.