There are many proofs of favourable impact of telecommunication and information technology (TIT) on economic growth and labour productivity in advanced economies in the 1990s. However, there are no studies estimating the TIT contribution to growth in the transition economies. So far, the lack or poor quality of available data have been the main obstacle. This article is the first attempt, based on an extended economic growth model, to estimate the impact of investment in TIT on economic growth and labour productivity in Poland. In the years 1995-2000, the average annual contribution of TIT capital to economic growth was 0.47 percentage point, which accounted for 8.9% of the average GDP growth in that period. At the same time, TIT capital also contributed to a 0.65 percentage point increase rise in labour productivity (accounting for 12.7% of its growth). The relatively high contribution of TIT capital is due to a very fast growth rate of investment in TIT in 1992-2001. This was, on the one hand, the consequence of a steep decline in prices for TIT goods and services and, on the other hand, the consequence of a sharp rise in demand for TIT, which was fuelled by fast economic growth in the 1990s and by a high level of unsatisfied demand for TIT, in connection with a substantial underinvestment of the information technology and telecommunication infrastructure.