This study investigates debt-equity variations and determinants with reference to quoted firms in Nigeria for the period 2009 to 2018. The major objective of the study is to ascertain the factors that influence the change in debt-equity. The data used is from fifteen listed firms in Nigeria, Preliminary analysis showed that income volatility, interest payment, asset tangibility, firm size and non-debt tax shield have high correlation with change in debt-equity ratio. All the independent variables are positively related to change in debt-equity ratio except income volatility. The panel unit root test showed that the data were all stationary at first differencing. The major findings indicated a positive and significant relationship between asset tangibility, firm size and change in debt-equity ratio of the selected firms. Interest payment and non-debt tax shield increased change in debt-equity ratio but insignificant, while income volatility showed a negative and insignificant effect on change in debt-equity ratio. The study recommends the need for quoted firms in Nigeria to provide quality management in various areas of the businesses activities to ensure the stability of income, without which can cause numerous businesses.