SUMMARYThe influence of paracetamol on antroduodenal motility and gastric pH was studied in 11 healthy subjects and the relationship between gastroduodenal motility and gastric emptying rate time,tmax, to peak concentration of serum paracetamol,Cmax, was evaluated. The incidence of antral phase III activity and the duration of phase III was diminished with paracetamol (P<0.05). The other motility parameters assessed were unchanged.Three patterns of motility and absorption were observed. One group (n= 5) were fast absorbers with atmaxof 1 h and a motility pattern characterized by antral activity, a high motility index and a short duration of phase II (33–60 min); the phase IIIs were complete except in one case. The second group (n= 4) hadtmaxat 1.5 h and their phase II motility was characterized by a longer duration (80–133 min) (P