Assessment of physical growth is one of the most important methods of determining nutrition and health status. Body mass index [BMI] is a suitable index for growth monitoring and helps in the identification of growth disorders and malnutrition in teenagers. The aim of this study was to determine BMI status in secondary school students in Kerman, Iran, in 2012. This was a descriptive-analytic study in which data were collected cross-sectionally and compared with the results of the study in 1997. After gaining permission from the Department of Education of Kerman, the samples were selected randomly from the secondary schools in Kerman. Height and weight were measured by standard tools. Data were analyzed through SPSS software and using Students’ independent t-test. Mean BMI of the students [n = 424] was 19 +/- 4.2 and 44.8% of students had normal BMI. Mean BMI of boys was significantly lower than girls. In total, 6% of the students were excessively thin and they were mainly from public schools in the suburb of the city. Over 50% of students had weight problems; underweight was the main problem in the studied population and only 9.2% of our subjects were overweight. Since the pubertal height and weight growth spurt occurs earlier in girls [10-13 years] than boys, the absolute comparison of BMI based on sex is not wise; if necessary it should to be performed after this period. Malnutrition or lack of access to food, or cultural factors and body shape care could explain our findings in regard to the distribution of BMI in the student population of Kerman