['To discuss the influence of age on the LA50 (the burn area lethal to 50% of patients) of burn patients.', '(1) Twenty-three thousand and seventy-three burn patients hospitalized in our center from December 1958 to December 2004 were enrolled, and they were divided into 25 age groups. LA50 values of total and full-thickness burn areas of patients in each age group were computed with probit regression method with Probit analysis of SPSS 11.0. (2) Those age groups with similar LA50 values were merged into one age group; thus 4 new age groups were formed. LA50 and its 95% confidence interval (CI) of total and full-thickness burn areas of patients in each age group were computed respectively. (3) All the patients were divided into group A (admitted from 1 December 1958 to 31 December 1983) and group B (admitted from 1 January 1984 to 31 December 2004) according to the admission time. LA50 and its 95% CI of total and full-thickness burn areas of patients in each age group of groups A and B were computed respectively.', '(1) LA50 values of total and full-thickness burn areas of patients among the 25 age groups were low in age groups younger than or equal to 5 years, which increased in age groups older than 5 years, distinctly higher in age groups older than 15 years, and they became lower in age groups older than 60 years. (2) LA50 values of total and full-thickness burn areas of patients in the 4 merged age groups were lowest in age groups older than 60 years (50.90% TBSA) and younger than or equal to 5 years (35.81% TBSA), and highest in age group older than 15 years and younger than or equal to 60 years (89.38% and 59.22% TBSA). There were statistically significant differences in LA50 of total and full-thickness burn areas of patients among 4 merged age groups [with 95% CI values of LA50 of total burn areas of patients in age groups ranging from young to old respectively (56.87 to 64.69)%, (64.46 to 74.36)%, (85.89 to 93.37)%, (44.55 to 60.73)% TBSA; with 95% CI values of LA50 of full-thickness burn areas of patients in age groups from young to old respectively (32.67 to 39.69)%, (40.86 to 50.41)%, (55.27 to 63.85)%, (32.46 to 54.86)% TBSA]. (3) LA50 values of total and full-thickness burn areas of patients in group B (98.94% and 73.23% TBSA) were significantly higher than those in group A (69.61% and 39.79% TBSA). There were differences in LA50 values of patients among different age groups in both group A and group B. The variation trend of LA50 values of patients among the 4 age groups in groups A and B was almost the same. Except for LA50 of total burn areas of patients in age group older than 5 years and younger than or equal to 15 years and LA50 of full-thickness burn areas of patients in age group older than 60 years, there were statistically significant differences in the LA50 of total and full-thickness burn areas of the other patients between group A and group B [with 95% CI of LA50 of total burn areas of patients of younger than or equal to 5 years, older than 15 years and younger than or equal to 60 years, and older than 60 years respectively (48.38 to 56.07)% and (68.68 to 81.35)% TBSA, (75.91 to 84.89)% and (97.09 to 110.45)% TBSA, (30.08 to 45.08)% and (60.67 to 102.69)% TBSA; with 95% CI of LA50 of full-thickness burn areas of patients of younger than or equal to 5 years, older than 5 years and younger than or equal to 15 years, older than 15 years and younger than or equal to 60 years respectively (27.48 to 34.69)% and (42.09 to 54.03)% TBSA, (34.78 to 46.43)% and (49.62 to 69.47)% TBSA, (43.98 to 51.77)% and (66.43 to 77.99)% TBSA].'] Do [ Influence of age on median lethal burn area of burn patients ]?