U suvremenom se hrvatskom jeziku pravi jednostavni niječni imperativi u pravilu tvore od nesvršenih glagola (Ne dirajte mi ravnicu!). U prvom slavenskom književnom jeziku, starocrkvenoslavenskom, niječni su se imperativi mogli tvoriti od svršenih glagola, pri čemu se u literaturi navodila djelomična podudarnost s grčkim jezikom, odnosno s grčkim konjunktivima prezenta i aorista. U radu se ispituje odnos svršenih i nesvršenih pravih niječnih imperativa u prvom hrvatskom književnom jeziku, hrvatskom crkvenoslavenskom, s posebnim naglaskom na odnos s latinskim jezikom predložaka. Komparativno korpusno istraživanje provedeno je na tekstu hrvatskoglagoljskoga II. beramskoga brevijara(15. st.). Analiza je podataka pokazala da se glagolski vid upotrebljava neovisno o latinskom predlošku. Osim toga, kvantitativni podaci sugeriraju da u hrvatskom crkvenoslavenskom razdoblju nije još došlo do zapaženijega potiskivanja uporabe svršenoga vida s pravim niječnim imperativima; In the contemporary Croatian language the true simple negative imperative is, in general, formed by using the imperfective aspect of a verb: (1) Ne dirajteIPFV mi ravnicu! *Ne dirnitePFV mi ravnicu! Not mess-2PL I-DAT.SG plain-ACC.SG ‘Don’t mess with my plain!’ In the first Slavic literary language, Old Church Slavonic, it was also possible to form a true simple negative imperative by using the perfective aspect of a verb. However, it was noticed in the literature that a partial congruence between the Old Church Slavonic imperfective and the perfective true negative imperative, on the one hand, and the Old Greek present and aorist subjunctive, on the other, existed. This paper looks at imperfective and perfective negative imperatives in the first Croatian literary language, Croatian Church Slavonic, with emphasis on the relationship with the Latin source texts. A comparative corpus analysis has been conducted on the Second Beram Breviary, a Croatian Glagolitic manuscript from the 15th century. The analysis shows that the usage of verb aspect in the Croatian Church Slavonic true simple negative imperative was independent of the influence of the Latin language. Also, the quantitative data suggest that no notable decline of perfective aspect with true simple imperative had occurred during the Croatian Church Slavonic period.