Arabis macdonaldiana is a species of flowering plant in the mustard family known by the common name MacDonald's rockcress.

It is native to northern California and Oregon, where it grows on newly exposed, barren serpentine soils in openings in temperate coniferous forest habitat.

It is a rare and endangered plant known from several sites in California and approximately two occurrences in Oregon, where it is threatened mainly by mining, particularly of nickel, which is one of several metals plentiful in the serpentine.

[1] This is a perennial herb growing one or more slender stems from a small, branching caudex, reaching 10 to 30 centimeters tall.

There is a basal patch of leaves with edges lined in small, widely spaced teeth which are sometimes tipped with spines.