The relationship between outcome and dose intensity was analyzed for first-line chemotherapy of advanced ovarian cancer using a particular CHAP (cyclophosphamide, hexamethylmelamine, Adriamycin [Adria Laboratories, Columbus, OH], cisplatin) regimen as the standard. Previously described techniques were used to calculate the average dose intensity of regimens containing one, two, three, or all four drugs of CHAP, relative to the standard. The average relative dose intensity, especially the relative dose intensity of cisplatin, correlated significantly with clinical response and with median survival time (MST) of the entire group (not just the remitters). There was a distinct advantage for multiagent regimens over single alkylating agents and especially for multiagent regimens containing cisplatin. Survival correlated with response rate (of multiagent regimens). This analysis suggests that dose intensity is a determinant of treatment outcome. Prospective randomized trials would be required to test whether, and to what extent, dose intensity determines outcome independently of total amount of drug given, performance status, or other factors. If dose intensity does determine outcome, methods of increasing it should be tested in an attempt to improve treatment results.