This study examines the relation between political connections and investment efficiency in China. For listed state-owned enterprises (SOEs), we find that the sensitivity of investment expenditure to investment opportunities is significantly weaker for those with than without political connections. Politically connected SOEs over-invest significantly more than non-connected SOEs. This negative impact of political connections is primarily observed in SOEs controlled by local governments and/or in SOEs without sufficient investment opportunities. However, for private enterprises, investment expenditure is significantly more sensitive to investment opportunities and over-investment is significantly less in politically connected firms than in those without such connections. We further show that over-investment reduces firm value across the board for both SOEs and private enterprises. Taken together, our findings suggest that political connections distort investment behavior, reduce investment efficiency, and damage firm value in listed SOEs in China, but for listed private enterprises, political connections improve investment efficiency, reduce over-investment, and consequently enhance firm value.