This study examined students’ perception on the causes and effects of mathematics anxiety among Senior Secondary Schools in Alimosho Local Government Area, Lagos State, Nigeria. The two instruments used for data collection were math anxiety scale adopted from Mutodi and Ngirande (2014) and researcher designed questionnaire titled causes and effects of math anxiety. The two instrument has reliability values of 0.78 and 0.76 respectively. Three hundred and twenty (320) students who were identified to have math anxiety using math anxiety scale were involved in the study. Data collected were analysed using frequency count, Simple percentage, Means and Binomial Test. The study revealed that Mathematics anxiety has significant negative effect on students’ performance in Mathematics. Also, the level of involvement of parents, teachers and peers towards students learning of Mathematics has significant relationship with mathematics anxiety among students. It was recommended that school management should ensure that students’ Mathematics anxiety is reduced by sensitizing Mathematics teachers not to be intimidating students with cane and other threats, encouraging teachers and others to help students solve mathematics problems. Also School management should ensure that adequate facilities are provided for the teaching and learning of mathematics.