The aim of this study was to epidemiologically characterize the appearance of clinical bovine respiratory disease complex (BRDC) in a Mexican feedlot. A retrospective study on 260211 records registered over a year and collected from animals housed in 210 pens was performed. In the study period, a total of 67467 steers were housed, with an incoming monthly average of 5190 ± 1252. There were 12783 BRDC clinical cases (18.9% of total steers), representing between 84.5 and 99.9% of all disease cases identified monthly in the pens (95.18 ± 5.10% sick animals per month). Other conditions requiring animal medication were lameness, diarrhea, and balanoposthitis. The average weight at BRDC first treatment was 335.71 ± 9.78 kg, but sick animals lost 15 kg. in average between the weight on arrival and the weight at first treatment. Average rectal temperature in animals affected by BRCD was 39.34 ± 0.94⁰C and 39.23 ± 0.67⁰C in relapsed steers. During the studied period 400 animals died (0.15% of the total), but only 105 died from BRCD (0.04% of the total). Overall monthly BRDC deaths represented 26.5% of total deaths, but the proportion of monthly deaths due to BRDC to the total number of deaths ranged between 0.22% and 48.1%, with higher values between July and September, 2010. BRDC lethality rate had an average value of 0.82% during the period, ranging monthly between 0.17 and 2.21 %. The average success of a first treatment against BRDC was 92.4%. Average monthly relapsed animals were 67 ± 41.3, ranging between 31 and 172 cases in April and February, respectively. Almost twice the number of sick animals was observed in winter (34%) than in fall, which had the lowest proportion of cases (18.1%); spring (22.4%) and summer (25.5%) had intermediate levels. The feedlot had only five animal suppliers, but most steers came from southern Veracruz (54.6%, 35190/67467). The percentage of BRDC sick animals by provenance of origin ranged from 3.68% (Tuxtepec, Oaxaca) to 19.15% (Chiapas). According to provenance, the number of relapsed animals ranged from one (Tuxtepec, Oaxaca) to 493 (south of Veracruz), but animals from more distant places (Tabasco and Chiapas), exhibited the highest value (between 7.65 and 7.85%). The heaviest and the lightest steers were more prone to BRDC relapse than animals in an average weight. Only 11 animals required a third treatment, five of which were treated in February. In conclusion, most susceptible steers to BRDC illness were those transported over larger distances, those which arrive in winter, as well as the heaviest and the lightest.