This systematic review analysed and synthesised the research done on effective science teacher professional development (PD) in post-apartheid South Africa, for the period 1994 to 2019, focusing on basic education. It investigated the efficacy of professional development models, with the aim of identifying models which positively impacted on science teachers and had the potential to improve teaching effectiveness. It also explored the issue of how South African researchers and education practioners evaluated the effectiveness of PD. Twenty articles were selected for analysis from electronic search of data bases. The findings reveal that 13 (65%) of the 20 analysed studies concluded that PD had a positive impact on participating teachers. Seven studies (35%) were either inconclusive or concluded that PD was ineffective. While researchers and education practioners have 'successfully' used a variety of PD models, the training and cascading models were the most popular. The results also show that, for all the reviewed studies, the evaluations of the effectiveness of PD only focused on what happened to the teacher and completely ignored determining the impact on students' learning outcomes, performance and achievement. It is recommended that future evaluations of science teacher PD efforts should take into account the effect or impact of the PD on students' learning outcomes, performance and achievement.