Derivatives of 2-amino-2-thiazoline exhibit muscarinomimetic properties in model experiments with isolated rat ileum. The activity of compounds strongly depends on the nature of substituents in 5-position of thiazoline ring. The most active spasmogenic compound is 5-iodomethyl-2-amino-2-thiazoline hydroiodide (EC50 = 13 +/- 2 microM). Its effect is very similar to activity of cholinergic agent pilocarpine (EC50 = 14 +/- 4 microM), but "intrinsic activity" parameter a (alpha = 0.87 +/- 0.12) of 5-iodomethyl-2-amino-2-thiazoline was more significant. Ileum contractions induced by this compounds were inhibited by atropine. Derivatives of 2-amino-2-thiazoline (like pilocarpine) were not demonstrated nicotinomimetic properties. These compounds demonstrate very weak anti-AChE activity. For 5-iodomethyl-2-amino-2-thiazoline hydroiodide the IC50 value is 0.39 +/- 0.09 mM.