The widespread application of word processors entails the use of grammar checkers. These tools are frequently employed by professional as well as unskilled language users. Some of the unskilled users, including pupils and students, tend to use such tools as an aid for their poor grammar knowledge. Therefore, questions are to be addressed concerning the efficiency and practical usefulness of such tools. The paper focuses on the analysis of the existing grammar checkers for Slovenian, namely Besana and LanguageTool, in terms of their precision, reliability, and practical usefulness. Firstly, both grammar checkers are briefly introduced emphasizing the crucial differences between them in terms of duration in their development as well as with regard to their financial and technical support. This is followed by a detailed description of the methods and materials used to design a practical experiment. In the experiment, the tools are examined from the point of view of the listed parameters when translating from Slovenian into English and from English into Slovenian. In addition, a hypothesis is also assessed claiming that the users of these tools trust the suggested error corrections more often when translating into a foreign language compared to translating into their mother tongue The findings are analysed using a typology of individual error categories developed specifically for this purpose. The results confirm the hypothesis tested and indicate a relatively high level of precision and reliability of both Besana and Languagetool, thus justifying the use of both grammar checkers for Slovenian. Nevertheless, they also suggest some possible upgrades to the tools discussed concerning their approach to error detection and their ability to suggest errors for users with varying levels of language competence.V prispevku smo na kratko predstavili dva obstoječa slovnična pregledovalnika za slovenščino, Besano in LanguageTool, in analizirali njuno uporabo z vidika natančnosti, zanesljivosti in praktične uporabnosti. Prav tako smo preverili hipotezo, da uporabniki danih orodij pogosteje upoštevajo predloge popravkov omenjenih orodij pri prevajanju v tuji jezik kot pri prevajanju v materni jezik. Izpostavili smo tudi izsledke, pridobljene pri proučevanju veljavnosti ene dodatnih predpostavk, ki se posredno nanaša na učinkovitost uporabe slovničnih pregledovalnikov. Prispevek ponuja možne odgovore na vprašanja o učinkovitosti in smiselnosti uporabe tovrstnih orodij, ki temeljijo na izsledkih praktičnega poskusa, v okviru katerega smo pričujoča orodja z vidika omenjenih parametrov proučevali pri prevajanju iz slovenščine v angleščino in iz angleščine v slovenščino. Za namen obdelave izsledkov smo razvili tipologijo posameznih kategorij napak, ki predstavlja enega od možnih pristopov za kvantitativno obdelavo izsledkov, pridobljenih pri raziskavah tovrstnih orodij z vidika parametrov natančnosti in zanesljivosti ter odnosa uporabnikov do predlogov popravkov. Izsledki danega poskusa upravičujejo uporabo obeh slovničnih pregledovalnikov za slovenščino, vendar obenem opozarjajo na posamezne možnosti za izboljšave teh orodij
