A new extraction method was developed for isolation of the antihistaminic drugs (histamine H2 receptor antagonists) famotidine (FMT) and nizatidine (NZT) from aqueous samples. A low solvent consumption method using dispersive liquid-liquid microextraction (DLLME) was applied for this purpose. The parameters of the isolation, namely, volume of extraction and disperser solvents, pH of sample and shaking time were optimized. The influence of foreign substances on the extraction process was also studied. After separation of FMT and NZT using DLLME, the analytes in organic extracts were determinated by high-performance liquid chromatography combined with UV spectrophotometry and liquid chromatography connected with tandem mass spectrometry (LC-MS-MS). The use of DLLME for selective isolation of analytes enables their preconcentration. Enrichment factors 23 and 61 were obtained for FMT and NZT, respectively. These procedures enable detection of the analytes in real samples at levels 0.24 μg mL-1 (limits of detection (LOD) of FMT: 7.2·10-7 mol L-1 and LOD of NZT: 7.3·10-7 mol L-1). The method was applied for the determination of the studied antihistaminic drugs in river water and wastewater samples. The use of LC-MS-MS in conjunction with DLLME enabled detection of FMT in Netta river at a concentration level of 0.46 ± 0.04 ng mL-1.