Biology knowledge and understanding is important not only for the conversion of the loftiest dreams into reality for a better life of individuals but also for preparing secondary pupils for such fields as agriculture, medicine, biotechnology, and genetic engineering. But a recent study has revealed that many aspects of school science (biology included) pose problems of understanding for pupils, simply because of the teaching methods used and the lack of adequate instructional resources. Nevertheless, a program was designed to incorporate the use of computer technology innovation called the computer-mediated simulations (CMS) program to enhance pupils' learning outcomes in school biology. The study was carried out in a real biology classroom setting. It involved comparisons between the treatment and control groups. A Solomon-Three Group quasi-experimental design was employed to involve three secondary schools situated along Njoro-Mau Narok and Elburgon-Molo roads in Nakuru district that were purposively sampled on the basis of easy accessibility and the availability of IBM compatible computers. A total of 102 pupils enrolled in three intact classes were exposed to the same content on cell division for a period of 3 weeks. Three dependent measures--the Biology Achievement Test (BAT), the Biology Classroom Environment Questionnaire (BCEQ), and the Pupil Attitude Questionnaire (PAQ)--were used to assess the effectiveness of the program on the pupils' academic achievement in cell theory, their perception of the classroom environment, and attitudes towards the biology course on cell theory. The findings of the study affirmed the impact of the CMS program on the pupils' learning outcomes in that the mean gains of the participants in the treatment groups were significantly higher than that of their counterparts in the regular program. Also, the results indicated that the mean differences between the experimental group and the true control group were statistically significant in favor of the treatment group. The findings also showed no relationship between the participants' gender and their learning outcomes. The study concludes that the use of the CMS program to augment conventional biology teaching has major implications for secondary biology instruction in this area.