Ocular blood flow was measured in aphakic rabbit eyes using a radioactive microsphere technique following sub-chronic three times a day treatment with one of the following drugs: ecothiophate iodide (0.125%), pilocarpine (4%), epinephrine (2%), norepinephrine (2%) or timolol (0.5%). The results show that regional ocular blood flow was statistically normal after this treatment regimen compared to both normal and aphakic control eyes. Ecothiophate did statistically increase choroidal blood flow and, although not statistically significant, other drugs did induce trends which may be relevant to drug use.