Assessment of science laboratory environment was conducted with 539 students at middle and high school. Science Laboratory Environment Inventory(SLEI) was used as an instrument. The major findings of this study are as follows. 1. Mean scores obtained on each scale in the actual and preferred version of SLEI were relatively low, particularly on the scale of open-endedness, integration, and material environment. 2. Mean scores obtained on each scale in the actual version were lower than those in the preferred version. Score differences between actual version and preferred one were found to be significant statistically. 3. Boys and high school students perceived their laboratory environment with more open-endedness and less rule clarity than girls and middle school students respectively. 4. Girls preferred student cohesiveness at their laboratory more than boys. Highschool students wanted open-ended environment more than middleschool students. 5. Each scale of SLEI showed significant correlation with the scores of attitudes toward science. Particularly open-endedness was found to account for a significant contribution to the affective outcomes.