The purpose of this study was to investigate whether time spent on indoor and outdoor activities or the other possible risk factors including age, gender, parental history, and initial refraction was associated with progression of myopia, during puberty. Fifty eyes of 50 myopic children aged 9-14 years were enrolled in the study. The parents were interviewed to determine the amounts of time in hours per day spent on reading and writing, using computer, watching TV, and outdoor activities (i.e., sports, games, or being outdoor with no activities) on an average day. The annual myopia progression rate (diopters per year) was calculated for each subject and was used in the statistical analyses. The mean initial age of the subjects was 10.9 +/- A 1.5 (ranging from 9 to 14) years. The mean follow-up period was 33.3 +/- A 10.3 (ranging from 17 to 55) months. There was a significant increase in the mean myopia value of the subjects after follow-up period (p < 0.001). The mean daily time spent on reading and writing and initial refraction value were independently associated with annual myopic progression rate. On the other hand, age, gender, parental myopia, and the mean daily times spent on computer use, watching TV, and outdoor activities had no correlations with annual myopia progression rate. The present study showed that myopia progression was associated with time spent on reading and writing and initial refraction value, during puberty. However, myopia progression was not associated with parental myopia, age, gender, and daily times spent on using computer, watching TV, and outdoor activities.