In an initial exploratory study, proneness to atopy was measured by specific allergen history, allergen skin testing and plasma IgE in couples with unexplained infertility and in a comparison group of couples who had recently had a child. At least one of the assessments was positive in 29 out of 47 infertile couples and in 52 out of 103 controls, but only five of the infertile group and two of the fertile group had all three assessments positive. Raised IgE levels occurred significantly more often in the infertile couples than in the comparison group.