This study investigated the implementation of e-learning in Nigerian secondary schools. The study specifically examined the challenges facing the implementation of e-learning, the availability of e-learning facilities and resources, the preparedness of teachers for e-learning implementation, the extent of students' participation in e-learning activities, and measures that can be adopted to improve e-learning implementation in Nigerian secondary schools. A descriptive survey research design was adopted for the study. The population comprised teachers and school administrators in selected secondary schools in Nigeria. A structured questionnaire titled E-learning Implementation in Nigerian Secondary Schools Questionnaire (EINSSQ) was used for data collection. The instrument was validated by experts in Educational Technology and Measurement and Evaluation. The data collected were analysed using mean and standard deviation to answer the research questions. The findings revealed that secondary schools in Nigeria face several challenges in implementing e-learning, including inadequate electricity supply, poor internet connectivity, insufficient ICT facilities, lack of technical support personnel, high cost of ICT equipment and maintenance, and inadequate funding. The study further found that some e-learning facilities and resources such as computers, computer laboratories, internet facilities, multimedia projectors, and e-learning software are available in schools, although advanced facilities such as interactive whiteboards are largely unavailable. The findings also indicated that teachers are moderately prepared for the implementation of e-learning, possessing basic computer skills and a reasonable level of confidence in integrating technology into teaching. Furthermore, students were found to participate in e-learning activities to a high extent through the use of computers, online learning materials, virtual classes, and electronic assignment submission. The study identified improved electricity supply, increased government funding, provision of adequate ICT facilities, affordable internet services, regular teacher training programmes, and employment of ICT support personnel as major measures for improving e-learning implementation.