Daily censuses of the hawksbill turtle Eretmochelys imbricata were taken during the nesting seasons 1995–2001 in three sandy beaches of the Yucatan Peninsula, Mexico (Celestun, El Cuyo and Isla Holbox), toevaluate aspects of its reproductive biology. A total of 9059 hawksbill turtle clutches was estimated for thestudy period. Nesting seasons began in mid-April and ended in early September, peaking in May–June.No significant differences were detected in the mean number of clutches per km among beaches. The largestnumber of clutches was observed in the supralittoral zone (6341: 70%), followed by the dune (2491: 27.5%)and the intertidal (227: 2.5%) zones. Variation in number of clutches showed a main peak in 1999,decreasing in 2000 and 2001. A significant decrease (3 cm) in body size of nesting females was detectedbetween 1995 and 2001. Mean clutch size was 140 eggs/clutch, and a significant positive relationshipbetween curved carapace length and mean clutch size was found at the three beaches. Incubation period,hatching success and emergence success varied between years (lowest values in 1998) and beaches (highestvalues at Isla Holbox), with no significant differences between the supralittoral and dune zones. Eventhough there was no evidence of a decreasing trend in nesting activity for the study period, the decreasein 2000–2001 suggests that additional beach monitoring is necessary to identify long-term trends, and toreduce potential losses of nests by human and natural causes in this globally important region for thehawksbill turtle.