This study is correlational research and aims to investigate the relationship between pre-service mathematics teachers' mathematical thinking levels and attitudes for courses in mathematics. We also examined whether gender, reasons for career choice, and academic achievement lead to significant differences in pre-service teachers' attitudes and mathematical thinking levels. Participants are 109 senior pre-service mathematics teachers from three different state universities that have similar conditions. Participants are selected via convenience sampling. Seventy-nine of the participants are female, and 30 are male. "Attitude scale for courses in mathematics" and "Mathematical Thinking Scale" are used to collect data. Data were analyzed by using SPSS package program. Pre-service teachers are found to have moderate attitudes while their mathematical thinking levels are at a high-level in the sub-domains of higher-order thinking tendency, reasoning, and problem-solving and at a moderate level in the subdomain of mathematical thinking skill. Pre-service teachers' attitudes for courses in mathematics have a significant moderate relationship with higher order thinking tendency, and reasoning and have a significant and weak relationship with problem-solving.