In the article was analysed service quality and its impact on firm’s profitability. The profitability factors in the economic activities were determined and the importance of profitability analysis was emphasized. Summarised profitability in telecommunications firms. In the article were listed analysed firms’ (for the analysis were selected services, which face high need from customers – services of Lithuania telecommunications firms LTD “Bitė Lietuva”, LTD “Omnitel”, LTD “Tele2”) service quality improvements as well as calculated profitability indexes. Statistical analysis and evaluation was made. The evaluation of the data shows, that LTD “Bitė Lietuva” indexes are correlated, but the correlation is not significant because of lack of data. Activity of LTD “Omnitel” shows, that improved service quality did not affect firm’s profitability. Improved service quality of LTD “Tele2” affected only part of analised profitability indexes. Inspite this the results show significant dependence.