Abstrak : Penelitian dilakukan untuk menganalisis apakah metode pembelajaran pemecahan masalah (Problem Solving) efektif dalam meningkatkan hasil belajar biologi siswa kelas X SMA Negeri 3 Mataram tahun pembelajaran 2010/2011. Jenis penelitian eksperimen semu. Populasi penelitian adalah semua kelas X SMA Negeri 3 Mataram tahun pembelajaran 2010/2011. Sampel penelitian ini adalah kelas X10 sebagai kelas kontrol dan kelas X12 sebagai kelas eksperimen dengan jumlah siswa masing-masing 31 orang. Pengambilan sampel dengan teknik Simple Random Sampling.Instrumen penelitian berupa tes hasil belajar, lembar observasi aktivitas guru dan siswa. Pre-tes dilakukan untuk mengetahui kemampuan awal dan Post-test untuk mengetahui hasil belajar siswa setelah diberikan perlakuan yang berbeda. Data hasil belajar kognitif dianalisis dengan menggunakan uji-t polled varians terhadap selisih nilai pre-test dan pos-test. Hasil penelitian diperoleh rata-rata kelas eksperimen lebih tinggi dari kelas kontrol, baik pada pre-test maupun post-test. Hasil uji hipotesis menunjukkan nilai t hitung> t tabel, yakni 2,987 > 1, 671 pada taraf kesalahan 5%, yang menunjukkan peningkatan hasil belajar yang signifikan. Data hasil belajar untuk aspek afektif dianalisis menggunakan skala penilaian dan aspek psikomotor menggunakan skala likert. Hasil penilaian menunjukkan peningkatan hasil belajar dengan rata-rata sangat baik pada kelas eksperimen, dan beberapa kategori baik dan kurang baik pada kelas kontrol. Hal tersebut menunjukkan bahwa penerapan metode Problem Solving efektif dalam meningkatkan hasil belajar biologi siswa kelas X SMA Negeri 3 Mataram tahun pembelajaran 2010/2011. Kata Kunci: metode Problem Solving, hasil belajar biologi Abstract: This research is aimed to analyze the effectiveness of problem solving methods to increase biological learning attainment of grade X student of Mataram High School in The Academic Year 2010/2011. This research used quasi experiment design. The population of the research was grade X students of Mataram Senior High School 3 in The Year 2010/2011. The samples of the research were 2 classes of 12 classes of grade X students. Student of the X10 was treated as experimental class and student of the X12 were untreated as control class. Simple random sampling was used to determined the sample, and observation sheet both of teacher and students were used as instrument in this research. Pretest was held to get information about students background knowledge of both classes and post test was held to know student achievement after given the treatment. The data of cognitive assessment was analysed using t- test polled variance according to difference between pretest and post test score. The result showed that everage score in experiment class was higher than the control class for both pretest or post test score. However, the t-test analyze suggest that the achievement of cognitive score was significantly in experimental class than the control class. The student assessment data of affective aspect was analyzed using score scale while psychomotoric aspect was analyzed using likert scale. The result shows that the experimental class achieved higher scale of category then the control class as this class achieved only medium and low category scale. This suggest that the application of problem solving learning methods was effective for increasing biological learning attainment of grade X student of Mataram Senior High School 3 in The Year of 2010/2011. Keywords: Problem Solving Methods, students learning attainment