本研究分析TIMSS 1999、2003、2007以及PISA 2006 台灣男女學生在科學表現上之性別差異。所有學生依照科學表現之分數分成四個人數相等的能力群組。檢視四組學生在平均值、標準差以及人數比例上的性別差異。結果發現，雖然整體男女生在科學表現的平均值差異不大，然而，男生分數的標準差一致的高於女生。高分組與低分組平均值差異、標準差比值以及人數比例上大部分有顯著差異。在低分組，女生平均分數高於男生，在高分組，則是男生平均分數高於女生。兩組的標準差都呈現男生大於女生，而高分組男生人數明顯多於女生。TIMSS與PISA在兩性差異上的結果並不一致。八年級的兩性差異似乎比四年級稍微大些。未來研究須注意樣本能力水準並採用多元的統計量數。

TIMSS 1999, 2003, 2007 and PISA 2006 data were used to investigate gender differences in the science performance. Each student was assigned to one quartile group (i.e., Q1 to Q4) based on his or her science performance. For each group, gender differences in mean scores, standard deviations, and numbers were examined. Results indicate that gender differences in mean scores are generally small. However, variances for males are higher than those for females. Most of gender differences in mean, standard deviation ratio, and male-to-female sample ratio from groups below Q1 and above Q3 are significant. Females outperform males in the group below Q1, while males outperform females among high-scoring group. In those two groups, the scores of male have larger variance. Males outnumber females substantially among high performance group. The patterns for gender differences from TIMSS and PISA are not the same. Gender gap in science performance score is slightly larger in grade 8 than in grade 4. It is suggested that in future research. The sample be better specified in terms of ability levels and gender differences be examined by multiple statistical indicators.