This article examines the influence of economics on business research using citation data. The share of economics in citations from business is 10.78% until 1995, but only 6.95% for 1996–2003. Four potential explanations for this decline are discussed: interdisciplinary spillover of research is slower than within a discipline; the increasing use of mathematics in economics made economics less useful for business scholars; economics articles are by their nature more long-lived than business articles; business has grown recently more quickly than economics. The data support the second and fourth explanations. Different research spillover occurs but lasts no more than two years.