We examine the determinants of capital structure of Malaysian companies utilizing data from 1984 to 1999. We classify data into four sub-periods that correspond to different stages of Malaysian capital market. Debt is decomposed into three categories: short-term, long-term and total debt. Both book value and market value debt ratios are calculated. The results of pooled OLS regressions show that profitability, size, growth, risk and tangibility variables have significant influence on all types of debt. These results are normally consistent with the results of fixed effect estimation with the exception that risk variable loses its significance. Unlike the evidence from the developed markets, investment opportunity (market-to-book value ratio) has no significant impact on debt policy in the emerging market of Malaysia. Our results are generally robust to time periods, but the significance of some variables changes over time. Profitability has a persistent and consistent negative relationship with all types of debt ratios in all periods and under all estimation methods. This confirms the capital structure prediction of the pecking order theory in an emerging capital market.