During a 6-month period 59 semen specimens were subjected to the direct immunobead test and 12 were positive (15% or more of sperm bound by IgA or IgG to the head, mid piece or principal piece of the tail, for an incidence of 20%). Mean motility and forward progression (scale of 0 to 4) were 47% (range 10 to 80) and 1.7 (range 1 to 3), respectively, in the positive test group, whereas these values were 53% (range 1 to 90) and 2.2 (range 1 to 3), respectively, in the negative test group. Sperm penetration assay was performed on 11 of the 12 direct immunobead test positive specimens. A normal sperm penetration assay score was noted in 5 of the 11 specimens (46%), a subfertile score in 4 (36%) and an infertile score (no penetrations) in 2 (18%). The incidence of scores in these 3 subcategories of fertility status in the direct immunobead test positive group did not differ significantly from distribution of scores from all 87 sperm penetration assays performed at our laboratory during the same period: normal--39 of 87 (45%), subfertile--35 (40%) and infertile--13 (15%). Furthermore, there was no pathognomonic binding pattern for those antibody positive patients with subfertile or infertile scores. In conclusion, sperm antibody positivity is typically independent of egg penetration ability, there is no pathognomonic antibody binding pattern for poor egg penetration and there is a tendency for antibody positive sperm to have a lower percentage of motility and forward progression.