This paper investigates the efficiency of German engineering firms and its change over time. As these firms had been successful in the past in terms of being market-leader, it is expected that the majority of the firms works efficiently. To analyze this question Farrell's technical efficiency is estimated using DEA. The results contradict these expectations. The engineering firms proved to operate quite inefficiently. Moreover, the results indicate that the efficiency of the firms is almost normally distributed and differs with company sizes. Besides, the measured efficiency changes are not consistent with the expectation of essentially small changes over time.