In this study we investigated the relationships between ceftazidime pharmacokinetic indices and clinical outcome measurements during acute pulmonary exacerbations in patients with cystic fibrosis. Twenty patients received ceftazidime during the study period. On Days 2, 7 and 14 outcome measurements were assessed. Ceftazidime peaks and troughs were calculated as was the percentage of time of the dosing interval the serum concentration/minimum inhibitory concentration ratio exceeded 8, 4 and 1. There were significant differences between Days 2 and 7 and between Days 2 and 14 for the outcome measurements. There were no significant between-day differences for the pharmacokinetic indices. Significant correlations, involving both within and between study days, existed between the ceftazidime pharmacokinetic indices and the clinical outcome measurements. Further investigation of these relationships is warranted.