Various 5-phenoxy derivatives of primaquine have been prepared that are somewhat more effective and considerably less toxic than the parent compound in blood and tissue schizonticidal screens. Addition of a methyl group to the pyridine ring of the 5-phenoxyprimaquines has produced a number of antimalarials with potent activity against both blood and tissue schizonts. Antimalarial enhancement of primaquine by 5-phenoxylation was described earlier. In an effort to achieve the optimal substitution pattern for this series, we have synthesized the compounds included in Table I. Having found that 4-methylprimaquine was less toxic than its parent, we were particularly interested in those primaquines that combined a 5-phenoxy with a pyridine ring methyl group. Chemistry. The preparative routes were essentially those described in paper 1 of this series. Details have been tabulated under Experimental Section.