Fertilization of the sea urchin egg is known to involve activation of a variety of protein kinases including at least one protein tyrosine kinase. In the present study, fertilization was found to stimulate the association of the Abl [correction of AbI] protein kinase with the detergent-insoluble egg cytoskeleton. Increased levels of Abl protein and of protein tyrosine kinase activity were detected in cytoskeleton preparations made as early as 5 to 15 min after insemination. Immunofluorescence localization demonstrated that the Abl kinase becomes associated primarily with the cortical cytoskeleton of the fertilized egg. A separate, 57 kDa protein tyrosine kinase did not associate with the cytoskeleton indicating that fertilization results in the selective association of the Abl kinase with the cortical cytoskeleton.