Solvent effects have been investigated for the last four decades. As far as we know, only 3 articles have reported on the solvent effect with beta-phosphorylated nitroxides. In 1976, Il'Yasov and coll. (Theor Exp Chem 12:656, 1976) showed in 16 solvents that the phosphorus hyperfine coupling constant a (P) linearly decreased with the polarity of the solvent given by the normalized Reichardt-Dimroth polarity constant E (N) (T) for in situ generated nitroxides, e.g., from a (P) = 40.80 G in n-hexane (E (T) (N) = 0.09) to a (P) = 22.80 G in water (E (T) (N) = 1). A few years later, Janzen and coll. (Magn Reson Chem 37:251-258, 1999) reported a weak (around 4 G) decrease in a (P) for a few beta-phosphorylated nitroxides in n-hexane and methanol. Recently, our group reported hardly any change in a (P) with the solvent for a very stable nitroxide, e.g., a (P) = 46.19 in n-pentane and a (P) = 45.60 in water. In this article, we report the solvent effect in 40 solvents on two new nitroxides and discuss at the light of the results reported in the literature. It turns out that a (P) changes obey no trends, i.e., strong or weak decrease, no change or even a weak increase in a (P) was observed depending on the structure of each nitroxide.