Giardiasis in pregnancy can be a debilitating disease with threatens the well-being of mother and fetus, as illustrated by three cases. The usual therapeutic agents are contraindicated in pregnancy. Paromomycin, an oral, poorly absorbed aminoglycoside, is an alternate, potentially less toxic agent for treatment of symptomatic giardiasis in pregnancy. The pharmacologic actions of paromomycin in human beings and its antiprotozoan efficacy are discussed.