An electron paramagnetic resonance (EPR) study of the Mn concentration and temperature in the range of 4 K ≤T≤300 K for the dilute semimagnetic semiconductor Zn1−xMnxIn2Se4 is reported. The EPR spectra were measured for the concentrations 0.01<x<1.0. For low Mn content the spectrum contains multiple resonances at g = 2, g~3 and g~5. The behaviour of the g = 2 signal linewidth ΔHpp as a function of temperature was studied and it was related to the fitting parameters at the critical temperature and the Curie point. The j parameter of the modified expression of Silva was obtained and its role is shown for the particular transition of this system.