Three commercial metalaxyl wettable powder (WP) formulations 15% were collected from different sources in Egypt as one of them was locally formulated and the other sources of formulations were ready-made from China and Jordan. The formulations under investigation were a mixture of metalaxyl and copper oxychloride currently applied in Egypt where this study was conducted to investigate the stability of metalaxyl as well as studying the formation of its relevant impurity 2, 6-dimethylaniline after storage at 54±2 ^oC and exposure to sunlight for different intervals. Identification and determination of metalaxyl and its relevant impurity content were achieved using GC–FID. From the obtained results metalaxyl showed that, high stability after storage at 54 ±2 ^oC, which resulted in a decrease in the rate of the formation of relevant impurity 2,6-dimethylaniline, on the other hand metalaxyl revealed that, slightly affected after exposure to sunlight compared to storage at 54 ±2 ^oC and the formation rate of relevant impurity was relatively higher than storage at 54 ±2 ^oC, but the amount of relevant impurity 2,6-dimethylaniline was in allowed limits for all sources before and after storage, in addition to that there was no a variation in the rate of degradation of metalaxyl and the amount of its relevant impurity 2,6-dimethylaniline for all sources under investigation.