Field studies were conducted in the sugarcane area of Los Mochis, Sinaloa, Mexico, from December 1994 to December 2001 to determine the establishment and impact of the introduced braconid Macrocentrus prolificus Wharton on the crambid stalkborers Diatraea considerata Heinrich, D. grandiosella Dyar, and Eoreuma loftini (Dyar). A total of ca. 200,000 M prolificus adults were liberated in each of five, 10-ha fields during May-December 1995. Fields were sampled monthly for stalkborer larvae and M prolificus parasitism from 1995 to 2001. Total stalkborer larvae averaged 2.9 per stalk during the period of study, with D. considerata, D. grandiosella, and E. loftini comprising 78.1, 21.2, and 0.7% of the total, respectively. Recovery of M prolificus from field-collected stalkborer larvae began soon after initial releases, with average parasitism 3% during 1995-1997, increasing to 6% in 1998, and stabilizing at 10-12% during 1999-2001. Average (all-years) parasitism was highest for D. considerata and lowest for E. loftini. none