The students’ attitudes towards school subjects may influence their behaviour and various educational outcomes. The research aimed to test students’ attitudes towards the subjects of Biology, Chemistry, and Physics, and to examine the associations between those attitudes and students’ learning strategies and grades achieved. The study included 245 eighth-grade students from five schools in Koprivnica-Križevci County in the Republic of Croatia. Attitude scale towards science subjects and Learning strategies scale were employed. The results of the analysis of variance showed a significantly higher assessment of interest for Biology and Physics than for Chemistry, while the assessment of importance for Biology was significantly higher than for Chemistry and Physics. Attitudes toward Biology, Chemistry, and Physics were positively correlated with the grades achieved in those subjects. Results of the mediation analysis indicated that the learning strategies were mediators between the attitude towards the science subject and the grades achieved in those subjects. Students with a more positive attitude towards a subject employ a deeper approach to learning, which ultimately results in a higher grade.