We studied the pharmacokinetics of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) and carboplatin administered in combination to 21 patients with advanced non-small cell lung cancer. Paclitaxel was administered as a 24-hour intravenous infusion at doses of 135 to 200 mg/m2. Carboplatin, dosed to a target area under the concentration-time curve of 5, 7, 9, or 11 mg/mL.min, was administered as a 20-minute infusion immediately following paclitaxel. Neither the paclitaxel concentrations at the end of the infusion nor the terminal elimination of paclitaxel, as assessed by the duration of time that plasma paclitaxel concentrations were 0.05 mumol/L or greater, were different compared with historical data of paclitaxel as a single agent. Thus, we concluded that carboplatin had no perceived effect on the pharmacokinetics of paclitaxel in this schedule. The observed areas under the concentration-time curves for carboplatin were consistently 10% to 15% less than the target values. Although this may indicate a possible interaction between paclitaxel and carboplatin, it also may have been a result of inadequate assessment of glomerular filtration rate, which was used to determine the carboplatin dose.