PC12 cells were cloned, and from their ability to form neurite-like processes 3 clones were selected: NGF-highly sensitive clone (HS), -moderately sensitive clone (MS), and -insensitive clone (IS). These clones were tested for the presence of specific NGF receptors by measuring the binding of 125I-labeled NGF. All 3 clones were capable of binding NGF, but the HS clone had more NGF receptors than the MS and IS clones. The effects of methyl mercuric chloride (MMC) and/or nerve growth factor (NGF) on these clones were tested. The HS clone was a little more susceptible to MMC than the MS and IS clones. When NGF was added to the culture medium in addition to MMC, cell recovery was observed. The tendency toward recovery was more prominent in the HS clone than in the IS one. Recovery in the MS clone was intermediate. These results suggest that NGF treatment can contribute to functional recovery of PC12 cloned cells from the cytotoxic effects of MMC depending on their ability to react to NGF.