Purpose We conducted a double-blind randomized clinical trial of the following four regimens for controlling delayed nausea (DN): group 1: palonosetron + dexamethasone on day 1 with prochlorperazine on days 2 and 3; group 2: granisetron + dexamethasone on day 1 with prochlorperazine on days 2 and 3; group 3: aprepitant + palonosetron + dexamethasone on day 1 with aprepitant + dexamethasone on days 2 and 3; and group 4: palonosetron + dexamethasone on day 1 with prochlorperazine + dexamethasone on days 2 and 3. Patients and Methods Chemotherapy-naive patients received doxorubicin, epirubicin, cisplatin, carboplatin, or oxaliplatin. The primary end point was average nausea assessed four times daily on days 2 and 3. Primary analyses were whether nausea control would be improved by using palonosetron versus granisetron on day 1 (group 1 v group 2); by adding dexamethasone on days 2 and 3 (group 1 v group 4); and by using aprepitant versus prochlorperazine (group 3 v group 4). Statistical significance was set at P = .017. Results Two hundred thirty-four, 234, 241, and 235 evaluable patients were accrued to groups 1, 2, 3, and 4, respectively. Adjusted mean differences for the three planned analyses were as follows: palonosetron versus granisetron: −0.01 (95% CI, −0.23 to 0.20; P = .72); adding dexamethasone on days 2 and 3: 0.20 (95% CI, −0.02 to 0.41; P = .01); and using aprepitant versus prochlorperazine: −0.03 (95% CI, −0.24 to 0.19; P = .56). Conclusion The addition of dexamethasone on days 2 and 3 reduced DN. Palonosetron and granisetron have similar effects on DN. The beneficial effect of adding aprepitant for control of DN was the same as adding prochlorperazine.