A study was conducted during three years to evaluate the alternate bearing production in pecan trees, Carya illinoensis (Wangenh) K. Koch. Results indicate that potential yields in the Comarca Lagunera region are of about two tons per hectare. In the observed plantations the annual alternate bearing index varied from 23 to 94%, with an mean of 52% that is high. The percentage of kernel decline when pecan production, inshell increases in after years. Al the regional level alternate bearing is not so big than in plantations because pecan production increases in after years. "Adult" (22‑29 years) and "mature" (33‑49 years) plantations showed an greater alternate bearing index and a lower kernel percentage than "young" plantations (12‑20 years). It is possible to obtain, pecan production inshell of about two tons per hectare and to reduce alternate bearing index when a 6‑10 m² per hectare of trees trunk cross sectional area occur.