Biology is a very important subject. It enables one to understand himself/herself and the surrounding environment. The knowledge acquired in Biology is applied in many fields such as medicine, pharmacy, nursing, dentistry and agriculture. Students’ performance in Biology at the Kenya Certificate of Secondary Education (KCSE) has been unsatisfactory over many years. Various reasons have been put forward by scholars to explain the cause of the poor performance. Students on the other hand have their reasons for the cause of the poor performance; hence the purpose of this research study was to investigate the factors that influence academic performance in Biology. The study aimed at finding out the attitudes of students towards Biology and how the attitudes influences their performance in Biology and also to find out the extent to which availability of teaching/learning resources influences performance in Biology. A descriptive survey design was used. Data was collected by use of questionnaires, observation checklists, interviews and document analysis. The sample for the study comprised 215 students drawn from 15 secondary schools in Uasin Gishu West District. The study respondents comprised form three students. Stratified random sampling was used to categorize schools into provincial, district and private. Simple random sampling was then used to select 15 schools from the 51 secondary schools in the district. At school level, the researcher applied simple random sampling technique to select 215 students who filled the questionnaires. The data was analyzed by use of descriptive statistics with the aid of SPSS computer programme. The data collected was coded, tabulated and represented using frequencies, tables and percentages. The study findings showed that, students with positive attitude towards the Biology subject, register better performance in examinations and also the availability of teaching/learning resources in schools impacted positively on students’ achievement in Biology examinations. The author of this paper recommends that: schools should motivate students so as to build on positive attitude towards sciences, so as to able to compete globally in the careers. Schools without teaching/learning resources should not be registered by the ministry of Education and schools should strive to build on good image.