The analysis of land-sea contrast in lightning activity in autumn on a regional scale is presented here. The lightning data over Bulgaria and Black Sea in September, October and November for 10 years (2005-2014) are used. Data for the time and the position of lightning are provided by the ZEUS network operating at the National Observatory of Athens. The investigation reveals that flash density in autumn during the studied 10 years is about 2 times higher over the Black Sea than over land (Bulgaria) and the maximum flash density occurs in September over the Black Sea. Diurnal variation of flash density (at 3-h time intervals) shows that the maximum of lightning activity in autumn is observed over the maritime area (Black sea) in the morning interval (0600-0900UTC). According to the results, lightning activity in most of the considered time intervals is higher over the Black Sea than over land, with the exception for the afternoon hours: in time interval (1200-1500 UTC) it is vice versa and in (1500-1800 UTC) - the flash density values are equal. The spatial distribution reveals that there are much more number of lightning over the southern part of the Black Sea, compared to the northern part of the basin. Over Bulgaria, the centers with the maximum number of lightning are over the mountains.