This study aims at investigating the impact of the irrigationmanagementfor tomato (Solanumlycopersicum 'Big Beef‘) grown under drip irrigation with mulch in an unheated polyethylene tunnel-type greenhouse.The experiment was carried out in the Chelopechene experimental field of the Institute of soil science, agrotechnologies and plant protection in town of Sofia, Bulgaria in 2018.Four different levels of irrigation have been served as treatment: T1 - full irrigation with application rate 100% of water requirements , T2 and T3 treatments – irrigationwith application rate 60% and 80% of the crop water requirements during the cluster fruit growing and cluster fruit ripening s and T4 - irrigation with 100% pan evaporation-based application rate.The total yield, yield per plant and irrigation water use efficiency (IWUE)were determined by treatments. The experimental results showed thatthe amount of water supplied for irrigation influencedfruit production of tomato grown in an unheated greenhouse.The highest tomato yield was obtained from the T1 and T4 treatments,89.205 t ha-1. и 88.11 t ha-1respectively. Reducing the irrigation application rate of 20% to 40% results in lower yield in T3 treatment by 10.5% and T2 treatment by 22% compared to the yield under full irrigation.The highest irrigation water use efficiency value of 27.03 kgm-3 was obtained for T2treatment the lowest irrigation level with. IWUE decreased in the other treatments as the amount of water applied for irrigation was larger.An economic analysis of the results was carried out.